Elastic substantially linear ethylene polymers

ABSTRACT

Elastic ethylene polymers are disclosed which have, processability similar to highly branched low density polyethylene (LDPE), but the strength and toughness of linear low density polyethylene (LLDPE). The polymers have processing indices (PI&#39;s) less than or equal to 70 percent of those of a comparative linear ethylene polymer and a critical shear rate at onset of surface melt fracture of at least 50 percent greater than the critical shear rate at the onset of surface melt fracture of a traditional linear ethylene polymer at about the same I 2  and M w /M n . The novel polymers can also have from about 0.01 to about 3 long chain branches/1000 total carbons and have higher low/zero shear viscosity and lower high shear viscosity than comparative liner ethylene polymers. T novel polymers can also be characterized as having a melt flow ratio, I 10 /I 2 ,≧5.63, a molecular weight distribution, M w /M n , defined by the equation: M w /M n ≦(I 10 /I 2 )−4.63, a critical shear stress at onset of gross melt fracture greater than about 4×10 6  dyne/cm 2 , and a single DSC melt peak between −30 C. and 150 C.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation-in-part of pending U.S.application Ser. No. 08/044,426 feed Apr. 7, 1993, which is a divisionalof U.S. application Ser. No. 07/776,130 filed Oct. 15, 1991, now U.S.Pat. No. 5,272,236. This application is also a continuation-in-part ofU.S. application Ser. No. 08/166,497 filed Dec. 13, 1993, which is adivisional of U.S. application Ser. No.07/939,281 filed Sep. 2, 1992which is now U.S. Pat. No. 5,278,272.

FIELD OF THE INVENTION

[0002] This invention relates to elastic substantially linear ethylenepolymers having improved processability. e.g., low susceptibilty to meltfracture, even under high shear stress conditions. Such substantiallylinear ethylene polymers have a critical shear rate at the onset ofsurface melt fracture substantially higher than, and a processing indexsubstantially less than, that of a linear polyethylene at the samemolecular weight distribution and melt index.

BACKGROUND OF THE INVENTION

[0003] Molecular weight distribution (MWD), or polydispersity, is a wellknown variable in polymers. The molecular weight distribution, sometimesdescribed as the ratio of weight average molecular weight (M_(w)) tonumber average molecular weight (M_(n)) (i.e., M_(w)/M_(n)) can be meddirectly, e.g., by gel permeation chromatography techniques, or moreroutinely, by measuring I₁₀/I₂ ratio, as described in ASTM D-1238. Forlinear polyolefins, especially linear polyethylene, it is well knownthat as M_(w)/M_(n) increases, I₁₀/I₂ also increases.

[0004] John Dealy in “Melt Rheology and Its Role in Plastics Processing”(Van Nostrand Reinhold, 1990) page 597 discloses that ASTM D-1238 isemployed with different loads in order to obtain an estimate of theshear rate dependence of melt viscosity, which is sensitive to weightaverage molecular weight (M_(w)) and number average molecular weight(M_(n))

[0005] Bersted in Journal of Applied Polymer Science Vol. 19, page2167-2177 (1975) theorized the relationship between molecular weightdistribution and steady shear melt viscosity for linear polymer systems.He also showed that the broader MWD material exhibits a higher shearrate or shear stress dependency.

[0006] Ramamurthy in Journal of Rheology, 30(2), 337-357 (1986), andMoynihan, Baird and Ramanathan in Journal of Non-Newtonian FluidMechanics, 36, 255-263 (1990), both disclose that the onset of sharkskin(i.e., surface melt fracture) for linear low density polyethylene(LLDPE) occurs at an apparent shear stress of 1-1.4×10⁶ dyne/cm², whichwas observed to be coincident with the change in slope of the flowcurve. Ramamurthy also discloses that the onset of surface melt fractureor of gross melt fracture for high pressure low density polyethylene(HP-LDPE) occurs at an apparent shear stress of about 0.13 MPa (1.3×10⁶dyne/cm²). Ramamurthy also discloses that “the corresponding shearstresses (0.14 and 0.43 MPa) for linear polyethylenes are widelyseparated.” However, these LLDPE resins are linear resins, and arebelieved to be those made by Union Carbide in their UNIPOL process(which uses conventional Ziegler-Natta catalysis which results in aheterogeneous comonomer distribution). The LLDPE is reported in Tables Iand II to have a broad M_(w)/M_(n) of 3.9. The melt fracture testsconducted by Ramamurthy were in the temperature range of 190 to 220 C.Furthermore, Ramamurthy reports that the onset of both surface and grossmelt fracture (for LLDPE resins) are “ . . . essentially independent ofMI (or molecular weight), melt temperature, die diameter (0.5-2.5 mm),die length/diameter ratio (2-20), and the die entry angle (includedangle: 60-180 degrees).”

[0007] Kalika and Denn in Journal of Rheology, 31, 815-834 (1987)confirmed the surface defects or sharkskin phenomena for LLDPE, but theresults of their work determined a critical shear stress at onset ofsurface melt fracture of 0.26 MPa, significantly higher than that foundby Ramamurthy and Moynihan et al. Kalika and Denn also report that theonset of gross melt fracture occurs at 0.43 MPa which is consistent withthat reported by Ramamurthy. The LLDPE resin tested by Kalika and Dennwas an antioxidant-modified (of unknown type) UNIPOL LLDPE having abroad M_(w)/M_(n) of 3.9. Kalika and Denn performed their melt fracturetests at 215 C. However, Kalika and Denn seemingly differ withRamamurthy in the effects of their L/D of the rheometer capillary.Kalika and Denn tested their LLDPE at L/D's of 33.2, 66.2, 100.1, and133.1 (see Table 1 and FIGS. 5 and 6).

[0008] International Patent Application (Publication No. WO 90/03414)published Apr. 5, 1990 to Exxon Chemical Company, discloses linearethylene interpolymer blends with narrow molecular weight distributionand narrow short chain branching distributions (SCBDs). The meltprocessibility of the interpolymer blends is controlled by blendingdifferent molecular weight interpolymers having different narrowmolecular weight distributions and different SCBDs.

[0009] Exxon Chemical Company, in the Preprints of Polyolefins VIIInternational Conference, page 45-66, Feb. 24-27, 1991, disclose thatthe narrow molecular weight distribution (NMWD) resins produced by theirEXXPOL™ technology have higher melt viscosity and lower melt strengththan conventional Ziegler resins at the same melt index. In a recentpublication, Exxon Chemical Company has also taught that NMWD polymersmade using a single site catalyst create the potential for melt fracture(“New Specialty Linear Polymers (SLP) For Power Cables,” by MonicaHendewerk and Lawrence Spenadel, presented at IEEE meeting in Dallas,Tex., September, 1991). In a similar vein, in “A New Family of LinearEthylene Polymers Provides Enhanced Sealing Performance” by Dirk G. F.Van der Sanden and Richard W. Halle, (February 1992 Tappi Journal),Exxon Chemical Company has also taught that the molecular weightdistribution of a polymer is described by the polymers melt index ratio(i.e., I₁₀/I₂) and that their new narrow molecular weight distributionpolymers made using a single site catalyst are “linear backbone resinscontaining no functional or long chain branches.”

[0010] U.S. Pat. No. 5,218,071 (Canadian patent application 2,008,315-A)to Mitsui Petrochemical Industries, Ltd., teaches ethylene copolymerscomposed of structural units (a) derived from ethylene and structuralunits (b) derived from alpha-olefins of 3-20 carbons atoms, saidethylene copolymers having [A] a density of 0.85-0.92 g/cm³, [B] anintrinsic viscosity as measured in decalin at 135 C. of 0.1-10 dl/g, [C]a ratio (M_(w)/M_(n)) of a weight average molecular weight (M_(w)) to anumber average molecular weight (M_(n)) as measured by GPC of 1.2-4, and[D] a ratio (MFR₁₀/MFR₂) of MFR₁₀ under a load of 10 kg to MFR₂ under aload of 2.16 kg at 190 C. of 8-50, and beign narrow in molecular weightdistribution and excellent in flowability. However, the ethylenecopolymers of U.S. Pat. No. '071 are made with a catalysis systemcomposed of methylaluminoxane and ethylenebis(indenyl)hafnium dichloride(derived from HfCl₄ containing 0.78% by weight of zirconium atoms ascontaminates). It is well known that mixed metal atom catalyst species(such as hafnium and zirconium in U.S. Pat. No. '071) polymerizescopolymer blends, which are evidence by multiple melting peaks. Suchcopolymer blends therefore are not homogeneous in terms of theirbranching distribution.

[0011] WO 85/04664 to BP Chemicals Ltd. teaches a process for thethermo-mechanical treatment of copolymers of ethylene and higheralpha-olefins of the linear low density polyethylene type with at leastone or more organic peroxides to produce copolymers that areparticularly well suited for extrusion or blow-molding into hollowbodies, sheathing, and the like. These treated copolymers show anincreased flow parameter (I₂₁/I₂) without significantly increasing theM_(w)/M_(n). However, the novel polymers of the present invention havelong chained branching and obtained this desirable result without theneed of a peroxide treatment

[0012] U.S. Pat. No. 5,096,867 discloses various ethylene polymers madeusing a single site catalyst in combinations with methyl aluminoxane.These polymers, in particular Example 47, have extremely high levels ofaluminum resulting from catalyst residue. When these aluminum residuesare removed from the polymer, the polymer exhibits gross melt fractureat a critical shear stress of less than 4×10⁶ dyne/cm².

[0013] All of the foregoing patents, applications, and articles areherein incorporated by reference.

[0014] Previously known narrow molecular weight distribution linearpolymers disadvantageously possessed low shear sensitivity or low I₁₀/I₂value, which limits the extrudability of such polymers. Additionally,such polymers possessed low melt elasticity, causing problems in meltfabrication such as film forming processes or blow molding processes(e.g., sustaining a bubble in the blown film process, or sag in the blowmolding process etc.). Finally, such resins also experienced meltfracture surface properties at relatively low extrusion rates therebyprocessing unacceptably.

SUMMARY OF THE INVENTION

[0015] A new class of homogeneous ethylene polymers have now beendiscovered which have long chain branching and unusual but desirablebulk properties. These new polymers include both homopolymers ofethylene and interpolymers of ethylene and at least one alpha-olefin.Both the homo- and interpolymers have long chain branching, but theinterpolymers have short chain branching in addition to the long chainbranching. The short chain branches are the residue of the alpha-olefinsthat are incorporated into the polymer backbone or in other words, theshort chain branches are that part of the alpha-olefin not incorporatedinto the polymer backbone. The length of the short chain branches is twocarbon atoms less than the length of the alpha-olefin comonomer. Theshort chain branches are randomly, i.e. uniformity, distributedthroughout the polymer as opposed to heterogeneously branchedethylene/alpha-olefin interpolymers such as conventional Zeigler LLDPE.

[0016] These novel ethylene polymers have a shear thinning and ease ofprocessability similar to highly branched low density polyethylene(LDPE), but with the strength and toughness of linear low densitypolyethylene (LLDPE). These novel ethylene polymers can also becharacterized as “substantially linear” polymers, whereby the bulkpolymer has an average of up to about 3 long chain branches 1000 totalcarbons or in other words, at least some of the polymer chains have longchain branching. The novel substantially linear ethylene polymers aredistinctly different from traditional Ziegler polymerized heterogeneouspolymers (e.g., LLDPE) and are also different from traditional freeradical/high pressure polymerized LDPE. Surprisingly, the novelsubstantially linear ethylene polymers are also different from linearhomogeneous ethylene polymers having a uniform comonomer distribution,especially with regard to processability.

[0017] These novel ethylene polymers, especially those with a densitygreater than or equal to about 0.9 g/cm³ are characterized as having:

[0018] a) a melt flow ratio, I₁₀/I₂,≧5.63,

[0019] b) a molecular weight distribution, M_(w)/M_(n), defined by theequation:

M _(w) /M _(n)≦(I ₁₀ /I ₂)−4.63,

[0020] c) a critical shear stress at onset of gross melt fracturegreater than about 4×10⁶ dyne/cm², and

[0021] d) a single melt peak as determined by differential scanningcalorimetry (DSC) between −30 and 150 C.

[0022] The novel ethylene polymers can also be characterized as having:

[0023] a) a melt flow ratio, I₁₀/I₂,≧5.63,

[0024] b) a molecular weight distribution, M_(w)/M_(n), defined by theequation:

M _(w) /M _(n)≦(I ₁₀ /I ₂)−4.63,

[0025] c) a critical shear rate at onset of surface melt fracture atleast 50 percent greater than the critical shear rate at the onset ofsurface melt fracture of a linear ethylene polymer with an I₂,M_(w)/M_(n), and density each within ten percent of the novel ethylenepolymer, and

[0026] d) a single melt peak as determined by differential scanningcalorimetry (DSC) between −30 and 150 C.

[0027] In another aspect, the novel ethylene polymers, especially thosehaving a density greater than or equal to about 0.9 g/cm³, arecharacterized as having:

[0028] a) a melt flow ratio, I₁₀/I₂,≧5.63, and

[0029] b) a molecular weight distribution, M_(w)/M_(n) of from about 1.5to about 2.5,

[0030] c) a critical shear stress at onset of gross melt fracturegreater than about 4×10⁶ dyne/cm², and

[0031] d) a single melt peak as determined by differential scanningcalorimetry (DSC) between −30 and 150 C.

[0032] In still another aspect, the novel ethylene polymers arecharacterized as having:

[0033] a) a melt flow ratio, I₁₀/I₂,≧5.63,

[0034] b) a molecular weight distribution, M_(w)/M_(n) of from about 1.5to about 2.5,

[0035] c) a critical shear rate at onset of surface melt fracture of atleast 50 percent greater than the critical shear rate at the onset ofsurface melt fracture of a linear ethylene polymer with an I₂,M_(w)/M_(n), and density each within ten percent of the novel ethylenepolymer, and

[0036] d) a single melt peak as determined by differential scanningcalorimetry (DSC) between −30 and 150 C.

[0037] The substantially linear ethylene polymers can also becharacterized as having a critical shear rate at onset of surface meltfracture of at least 50 percent greater than the critical shear rate atthe onset of surface melt fracture of a linear ethylene polymer havingan I₂, M_(w)/M_(n) and density each within ten percent of thesubstantially linear ethylene polymer.

[0038] In still another aspect the novel polymer can be characterized asa substantially linear ethylene bulk polymer having:

[0039] (a) and average of about 0.01 to about 3 long chain branches/1000total carbons,

[0040] (b) a critical shear stress at onset of gross melt fracture ofgreater than about 4×10⁶ dyne/cm², and

[0041] (c) a single DSC melt peak between −30 and 150 C.

[0042] The substantially linear ethylene bulk polymer can also becharacterized as having:

[0043] (a) an average of about 0.01 to about 3 long chain branches/1000total carbons,

[0044] (b) a critical shear rate at onset of surface melt fracture of atleast 50 percent greater than the critical shear rate at the onset ofsurface melt fracture of a linear ethylene polymer having an I₂,M_(w)/M_(n) and density each within ten percent of the substantiallylinear ethylene bulk polymer, and

[0045] (c) a single DSC melt peak between −30 and 150 C.

[0046] In still another aspect, the ethylene polymer can becharacterized as a substantially linear ethylene bulk polymer having:

[0047] (a) and average of about 0.01 to about 3 long chain branches/1000total carbons,

[0048] (b) a melt flow ratio, I₁₀/I₂,≧5.63,

[0049] (c) a molecular weight distribution, M_(w)/M_(n), from about 1.5to about 2.5, and

[0050] (d) a single DSC melt peak between −30 and 150 C.

[0051] The novel ethylene polymers, especially the substantially linearethylene polymers, also have a processing index (PI) less than or equalto about 70 percent of the PI of a linear ethylene polymer at about thesame I₂, M_(w)/M_(n), and density each within ten percent of the novelethylene polymer.

[0052] Compositions comprising the novel ethylene polymer and at leastone other natural or synthetic polymer are also within the scope of theinvention.

[0053] Elastic substantially linear ethylene polymers comprisingethylene homopolymers or an interpolymer of ethylene with at least oneC₃-C₂₀ alpha-olefin copolymers are especially preferred.

BRIEF DESCRIPTION OF THE DRAWINGS

[0054]FIG. 1 is a schematic representation of a polymerization processsuitable for making the polymers of the present invention.

[0055]FIG. 2 plots data describing the relationship between I₁₀/I₂ andM_(w)/M_(n) for two examples of the invention, and for some comparativeexamples.

[0056]FIG. 3 plots the shear stress versus shear rate for an Example ofthe invention and for a Comparative Example, described herein.

[0057]FIG. 4 plots the shear stress versus shear rate for an Example ofthe invention and for a Comparative Example, described herein.

[0058]FIG. 5 plots the heat seal strength versus heat seal temperatureof film made from Examples of the invention, and for ComparativeExamples, described herein.

[0059]FIG. 6 graphically displays dynamic shear viscosity data for anelastic substantially linear ethylene polymer of the present inventionand for a comparative linear polymer made using single site catalysttechnology.

[0060]FIG. 7 graphically displays I₁₀/I₂ ratio as a function of ethyleneconcentration in the polymerization reactor for ethylene/propenesubstantially linear copolymers of the invention.

[0061]FIG. 8 graphically displays the melting curves for a comparativepolymer made according to U.S. Pat. No. 5,218,071 (Mitsui).

[0062]FIG. 9 graphically displays the structural characteristics of atraditional heterogeneous Ziegler polymerized LLDPE copolymers, a highlybranched high pressure-free radical LDPE, and a novel substantiallylinear ethylene/alpha-olefin copolymer of the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0063] The term “linear” as used herein means that the ethylene polymerdoes not have long chain branching. That is, the polymer chainscomprising the bulk linear ethylene polymer have an absence of longchain branching, as for example the traditional linear low densitypolyethylene polymers or linear high density polyethylene polymers madeusing Ziegler polymerization processes (e.g., U.S. Pat. No. 4,076,698(Anderson et al.)), sometimes called heterogeneous polymers. The term“linear” does not refer to bulk high pressure branched polyethylene,ethylene/vinyl acetate copolymers, or ethylene/vinyl alcohol copolymerswhich are known to those skilled in the art to have numerous long chainbranches. The term “linear” also refers to polymers made using uniformbranching distribution polymerization processes, sometimes calledhomogeneous polymers, including narrow MWD (e.g. about 2) made usingsingle site catalysts. Such uniformly branched or homogeneous polymersinclude those made as described in U.S. Pat. No. 3,645,992 (Elston) andthose made using so-called single site catalysts in a batch reactorhaving relatively high ethylene concentrations (as described in U.S.Pat. No. 5,026,798 (Canich) or in U.S. Pat. No. 5,055,438 (Canich)) orthose made using constrained geometry catalysts in a batch reactor alsohaving relatively high olefin concentrations (as described in U.S. Pat.No. 5,064,802 (Stevens et al.) or in EP 0 416 815 A2 (Stevens et al.)).The uniformly branched/homogeneous polymers are those polymers in whichthe comonomer is randomly distributed within a given interpolymermolecule or chain, and wherein substantially all of the interpolymermolecules have the same ethylene/comonomer ratio within thatinterpolymer, but these polymers too have an absence of long chainbranching, as, for example. Exxon Chemical has taught in their February1992 Tappi Journal paper. For example, FIG. 9 shows the structuraldifferences among conventional heterogeneously branched LLDPE,homogeneously branched linear LLDPE, highly branched high pressure, freeradical LDPE, and the homogeneously branched substantially linearethylene polymers of the present invention.

[0064] The term “substantially linear” as used means that the bulkpolymer is substituted, on average, with about 0.01 long chainbranches/1000 total carbons (including both backbone and branch carbons)to about 3 long chain branches/1000 total carbons. Preferred polymersare substituted with about 0.01 long chain branches/1000 total carbonsto about 1 long chain branches/1000 total carbons, more preferably fromabout 0.05 long chain branches/1000 total carbons to about 1 long chainbranched/1000 total carbons, and especially from about 0.3 long chainbranches/1000 total carbons to about 1 long chain branches/1000 totalcarbons.

[0065] As used herein, the term “backbone” refers to a discretemolecule, and the term “polymer” or “bulk polymer” refers in theconventional sense to the polmer as formed in a reactor. For the polymerto be a “substantially linear” polymer, the polymer must have at leastenough molecules with long chain branching such that the average longchain branching in the bulk polymer is at least an average of about0.01/1000 total carbons.

[0066] The term “bulk” polymer means the polymer which results from thepolymerization process and, for the substantially linear polymers,includes molecules having both an absence of long chain branching, aswell as molecules having long chain branching. Thus a “bulk” polymerincludes all molecules formed during polymerization. It is understoodthat, for the substantially linear polymers, not all molecules have longchain branching, but a sufficient amount do such that the average longchain branching content of the bulk polymer positively affects the meltrheology (i.e., the melt fracture properties).

[0067] Long chain branching (LCB) is defined herein as a chain length ofat least one (1) carbon less than the number of carbons in thecomonomer, whereas short chain branching (SCB) is defined herein as achain length of the same number of carbons in the residue of thecomonomer after it is incorporated into the polymer molecule backbone.For example, an ethylene/1-octene substantially linear polymer hasbackbones with long chain branches of at least seven (7) carbons inlength, but it also has short chain branches of only six (6) carbons inlength.

[0068] Long chain branching can be distinguished from short chainbranching by using ¹³C nuclear magnetic resonance (NMR) spectroscopy andto a limited extent, e.g. for ethylene homopolymers, it can bequantified using the method of Randall (Rev. Macromol. Chem. Phys., C29(2&3), p. 285-297), the disclosure of which is incorporated herein byreference. However as a practical matter, current ¹³C nuclear magneticresonance spectroscopy cannot determine the length of a long chainbranch in excess of about six (6) carbon atoms and as such, thisanalytical technique cannot distinguish between a seven (7) carbonbranch and a seventy (70) carbon branch. The long chain branch can be aslong as about the same length as the length of the polymer back-bone.

[0069] U.S. Pat. No. 4,500,648, incorporated herein by reference,teaches that long chain branching frequeny (LCB) can be represented bythe equation LCB=b/M_(w) wherein b is the weight average number of longchain branches per molecule and M_(w) is the weight average molecularweight. The molecular weight averages and the long chain branchingcharacteristics are determined by gel permeation chromatography andintrinsic viscosity methods.

[0070] Similar to the traditional homogeneous polymers, thesubstantially linear ethylene/alpha-olefin copolymers of the inventionhave only a single melting point, as opposed to traditional Zieglerpolymerized heterogeneous linear ethylene/alpha-olefin copolymers whichhave two or more melting points (determined using differential scanningcalorimetry (DSC)). Ethylene polymers of this invention are alsocharacterized by a single DSC melting peak between −30 and 150 C.However, those polymers having a density of about 0.875 g/cm³ to about0.91 g/cm³, the single melt peak may show, depending on equipmentsensitivity, a “shoulder” or a “hump” on the side low of the meltingpeak (i.e. below the melting point) that constitutes less than 12percent, typically, less than 9 percent, more typically less than 6percent of the total heat of fusion of the polymer. This artifact is dueto intrapolymer chain variations, and it is discerned on the basis ofthe slope of the single melting peak varying montonically through themelting region of the artifact Such artifact occurs within 34 C.,typically within 27 C., and more typically within 20 C. of the meltingpoint of the single melting peak. The single melting peak is determinedusing a differential scanning calorimeter standardized with indium anddeionized water. The method involves about 5-7 mg sample sizes, a “firstheat” to about 150 C. which is held for 4 minutes, a cool down at10/min. to −30 C. which is held for 3 minutes, and heat up at 10 C./min.to 150 C. for the “second heat” heat flow vs. temperature curve. Totalheat of fusion of the polymer is calculated from the area under thecurve. The heat of fusion attributable to this artifact, if present, canbe determined using an analytical balance and weight-percentcalculations.

[0071]FIG. 8 displays the melting curves for a polymer of the inventionand for a comparative polymer as described in U.S. Pat. No. 5,218,071(Mitsui). Note that the comparative polymer has two melting peaks (thehigh melting peak with a shoulder on its high side, i.e. above thesecond melting point), and this is indicative of the presence of twodistinct polymers (as opposed to the melting curve of the inventionpolymer having only a single melting peak).

[0072] The SCBDI (Short Chain Branch Distribution Index) or CDBI(Composition Distribution Branch Index) is defined as the weight percentof the polymer molecules having a comonomer content within 50 percent ofthe median total molar comonomer content. The CDBI of a polymer isreadily calculated from data obtained from techniques known in the art,such as, for example, temperature rising elution fractionation(abbreviated herein as “TREF”) as described for example, in Wild et al,Journal of Polymer Science, Poly. Phys. Ed., Vol. 20, p. 441 (1982), oras described in U.S. Pat. No. 4,798,081. The SCBDI or CDBI for thesubstantially linear ethylene polymers of the present invention istypically greater than about 30 percent, preferably greater than about50 percent, more preferably greater than about 80 percent, and mostpreferably greater than about 90 percent.

[0073] “Melt tension” is measured by a specially designed pulleytransducer in conjunction with the melt indexer. Melt tension is theload that the extrudate or filament exerts while passing over the pulleyonto a two inch drum that is rotating at the standard speed of 30 rpm.The melt tension measurement is similar to the “Melt Tension Tester”made by Toyoseiki and is described by John Dealy in “Rheometers forMolten Plastics”, published by Van Nostrand Reinhold Co. (1982) on page250-251. The melt tension of these new polymers is also surprisinglygood, e.g., as high as about 2 grams or more. For the novelsubstantially linear ethylene interpolymers of this invention,especially those having a very narrow molecular weight distribution(i.e., M_(w)/M_(n) from 1.5 to 2.5), the melt tension is typically atleast about 5 percent, and can be as much as about 60 percent, greaterthan the melt tension of a conventional linear ethylene interpolymerhaving a melt index, polydispersity and density each within ten percentof the substantially linear ethylene polymer.

[0074] A unique characteristic of the presently claimed polymers is ahighly unexpected flow property where the I₁₀/I₂ value is essentiallyindependent of polydispersity index (i.e. M_(w)/M_(n)). This iscontrasted with conventional Ziegler polymerized heterogeneouspolyethylene resins and with conventional single site catalystpolymerized homogeneous polyethylene resins having rheologicalproperties such that as the polydispersity index increases, the I₁₀/I₂value also increases.

[0075] The density of the neat ethylene or substantially linear ethylenepolymers of this invention, i.e. polymers without inorganic fillers andnot containing in excess of 20 ppm aluminum from catalyst residue, ismeasured in accordance with ASTM D-792. The ethylene or substantiallylinear ethylene polymers are crystalline and/or semicrystallinepolymers, are normally solid at room temperature, and are pelletizableat ambient conditions or at temperatures induced by cooled water. Forexample, a novel substantially linear ethylene/1-octene copolymer havinga density of 0.865 g/cm³ has about 10% crystallinity at roomtemperature. The minimum density is typically at least about 0.865 g/cm³preferably at least about 0.870 g/cm³, and more preferably at leastabout 0.900 g/cm³. The maximum density typically does not exceed about0.970 g/cm³, preferably it does not exceed about 0.940 g/cm³, and morepreferably it does not exceed about 0.92 g/cm³.

[0076] The molecular weight of the ethylene or ethylene/alpha-olefinsubstantially linear ethylene polymers in the present invention isconveniently indicated using a melt index measurement according to ASTMD-1238, Condition 190 C/2.16 kg (formally known as “Condition (E)” andalso known as I₂). Melt index is inversely proportional to the molecularweight of the polymer. Thus, the higher the molecular weight, the lowerthe melt index, although the relationship is not linear. The melt indexfor the ethylene or ethylene/alpha-olefin substantially linear ethylenepolymers used herein is generally from about 0.01 grams/10 minutes (g/10min) to about 1000 g/10 min, preferably from about 0.01 g/10 min toabout 100 g/10 min, and especially from about 0.01 g/10 min to about 10g/10 min.

[0077] Another measurement useful in characterizing the molecular weightof the substantially linear ethylene polymers is conveniently indicatedusing a melt index measurement according to ASTM D-1238, Condition190C/10 kg (formerly known as “Condition (N)” and also known as I₁₀).The ratio of these two melt index terms is the melt flow ratio and isdesignated as I₁₀/I₂. For the substantially linear ethylene/alpha-olefinpolymers of the invention, the I₁₀/I₂ ratio indicates the degree of longchain branching, i.e., the higher the I₁₀/I₂ ratio, the more long chainbranching in the polymer. Generally, the I₁₀/I₂ ratio of thesubstantially linear ethylene/′-olefin polymers is at least about 5.63,preferably at least about 7, especially at least about 8, mostespecially at least about 9 or above. The only limitations on themaximum I₁₀/I₂ ratio are practical considerations such as economics,polymerization kinetics, etc., but typically the maximum I₁₀/I₂ ratiodoes not exceed about 20, and preferably it does not exceed about 15.

[0078] Antioxidants (e.g., hindered phenolics (e.g., Irganox® 1010 madeby Ciba Geigy Corp.), phosphites (e.g., Irgafos® 168 made by Ciba GeigyCorp.)), are preferably added to protect the polymer from degradationduring thermal processing steps such as pelletization, molding,extrusion, and characterization methods. Other additives to servespecial functional needs include cling additives, e.g. PIB, antiblocks,antislips, pigments, fillers. In-process additives, e.g. calciumstearate, water, etc., may also be used for other purposes such as forthe deactivation of residual catalyst. However, peroxide need not beadded to the novel polymers in order for the polymers to exhibit anI₁₀/I₂ independent of the MWD and the melt fracture properties.

[0079] Molecular Weight Distribution Determination

[0080] The whole interpolymer product samples and the individualinterpolymer samples are analyzed by gel permeation chromatography (GPC)on a Waters 150 C. high temperature chromatographic unit equipped withthree linear mixed porosity bed columns (available from PolymerLaboratories), operating at a system temperature of 140 C. The solventis 1,2,4-trichlorobenzene, from which 0.3 percent by weight solutions ofthe samples are prepared for injection. The flow rate is 1.0milliliters/minute and the injection size is 200 microliters.

[0081] The molecular weight determination is deduced by using narrowmolecular weight distribution polystyrene standards (from PolymerLaboratories) in conjunction with their elution volumes. The equivalentpolyethylene molecular weights are determined by using appropriateMark-Houwink coefficients for polyethylene and polystyrene (as describedby Williams and Ward in Journal of Polymer Science, Polymer Letters,Vol. 6, (621) 1968) to derive the following equation:

M _(polyethylene) =a*(M _(polystyrene))^(b).

[0082] In this equation, a=0.4316 and b=1.0 for polyethylene andpolystyrene in 1,2,4-trichlorobenzene. Weight average molecular weight,M_(w), is calculated in the usual manner according to the followingformula: M_(w)=εw_(i)*M_(i), where w_(i) and M_(i) are the weightfraction and molecular weight, respectively, of the i^(th) fractioneluting from the GPC column.

[0083] The molecular weight distribution (M_(w)/M_(n)) for thesubstantially linear ethylene polymers of the invention is generallyless than about 5, preferably from about 1.5 to about 2.5, andespecially from about 1.7 to about 2.3.

[0084] Processing Index Determination

[0085] The “rheological processing index” (PI) is the apparent viscosity(in kpoise) of a polymer and is measured by a gas extrusion rheometer(GER). The GER is described by M. Shida, R. N. Shroff and L. V. Cancioin Polym. Eng. Sci., Vol. 17, no. 11, p. 770 (1977), and in “Rheometersfor Molten Plastics” by John Dealy, published by Van Nostrand ReinholdCo. (1982) on page 97-99, the disclosures of both of which areincorporated in their entirety herein by reference. The processing indexis measured at a temperature of 190 C., at nitrogen pressure of 2500psig using a 0.0296 inch (752 micrometers) diameter (preferably 0.0143inch diameter die for high flow polymers, e.g. 50-100 melt index orgreater), 20:1 L/D die having an entrance angle of 180 degrees. The GERprocessing-index is calculated in millipoise units from the followingequation:

PI=2.15×10⁶ dyne/cm ²/(1000×shear rate),

[0086] where: 2.15×10⁶ dyne/cm² is the shear stress at 2500 psi and theshear rate is the shear rate at the wall as represented by the followingequation:

32 Q′/(60 sec/min)(0.745)(Diameter×2.54 cm/in)³, where:

[0087] Q′ is the extrusion rate (gms/min),

[0088] 0.745 is the melt density of polyethylene (gm/cm³), and

[0089] Diameter is the orifice diameter of the capillary (inches).

[0090] The PI is the apparent viscosity of a material measured atapparent shear stress of 2.15×10⁶ dyne/cm².

[0091] For the substantially linear ethylene polymers (orethylene/alpha-olefin copolymers or interpolymers), the PI is less thanor equal to 70 percent of that of a conventional linear ethylene polymer(or ethylene/alpha-olefin copolymer or interpolymer) having an I₂,M_(w)/M_(n) and density each within ten percent of the substantiallylinear ethylene polymer.

[0092] An apparent shear stress vs. apparent shear rate plot is used toidentify the melt fracture phenomena over a range of nitrogen pressesfrom 5250 to 500 psig using the die or GER test apparatus previouslydescribed According to Ramamurthy in Journal of Rheology, 30(2),337-357, 1986, above a certain critical flow rate, the observedextrudate irregularities may be broadly classified into two main types:surface melt fracture and gross melt fracture.

[0093] Surface melt fracture occurs under apparently steady flowconditions and ranges in detail from loss of specular gloss to the moresevere form of “sharkskin”. In this disclosure, the onset of surfacemelt fracture is characterized at the beginning of losing extrudategloss at which the surface roughness of extrudate can only be detectedby 40× magnification. The critical shear rate at onset of surface meltfracture for the substantially linear ethylene polymers is at least 50percent greater than the critical shear rate at the onset of surfacemelt fracture of a linear ethylene polymer having about the same I₂ andM_(w)/M_(n). Preferably, the critical shear stress at onset of surfacemelt fracture for the substantially linear ethylene polymers of theinvention is greater than about 2.8×10⁶ dyne/cm².

[0094] Gross melt fracture occurs at unsteady flow conditions and rangesin detail from regular (alternating rough and smooth, helical, etc.) torandom distortions. For commercial acceptability, (e.g., in blown filmproducts), surface defects should be minimal, if not absent. Thecritical shear rate at onset of surface melt fracture (OSMF) andcritical shear stress at onset of gross melt fracture (OGMF) will beused herein based on the changes of surface roughness and configurationsof the extrudates extruded by a GER For the substantially linearethylene polymers of the invention, the critical shear stress at onsetof gross melt fracture is preferably greater than about 4×10⁶ dyne/cm².

[0095] For the processing index deterination and for the GER meltfracture determination, the novel ethylene or substantially linearethylene copolymers are tested without inorganic fillers, and they donot have more than 20 ppm aluminum catalyst residue. Preferably,however, for the processing index and melt fracture tests, the novelethylene polymers and substantially linear ethylene copolymers docontain antioxidants such as phenols, hindered phenols, phosphites orphosphonites, preferably a combination of a phenol or hindered phenoland a phosphite or a phosphonite.

[0096] The Constrained Geometry Catalyst

[0097] Suitable constrained geometry catalysts for use herein preferablyinclude constrained geometry catalysts as disclosed in U.S. applicationSer. Nos. 545,403, filed Jul. 3, 1990; 758,654, filed Sep. 12, 1991;758,660, filed Sep. 12, 1991; and 720,041, filed Jun. 24, 1991. Themonocyclopentadienyl transition metal olefin polymerization catalyststaught in U.S. Pat. No. 5,026,798 which is incorporated herein byreference, are also believed to be suitable for use in preparing thepolymers of the present invention, so long as the polymerizationconditions substantially conform to those.

[0098] The foregoing catalysts may be further described as comprising ametal coordination complex comprising a metal of groups 3-10 or theLanthanide series of the Periodic Table of the Elements and adelocalized B-bonded moiety substituted with a constrain-inducingmoiety, said complex having a constrained geometry about the metal atomsuch that the angle at the metal between the centroid of thedelocalized, substituted pi-bonded moiety and the center of at least oneremaining substituent is less than such angle in a similar complexcontaining a similar pi-bonded moiety lacking in such constrain-inducingsubstituent, and provided further that for such complexes comprisingmore than one delocalized, substituted pi-bonded moiety, only onethereof for each metal atom of the complex is a cyclic, delocalized,substituted pi-bonded moiety. The catalyst further comprises anactivating cocatalyst.

[0099] Preferred catalyst complexes correspond to the formula:

[0100] wherein:

[0101] M is a metal of group 3-10, or the Lanthanide series of thePeriodic Table of the Elements;

[0102] Cp* is a cyclopentadienyl or substituted cyclopentadienyl groupbound in an eta⁵ bonding mode to M;

[0103] Z is a moiety comprising boron, or a member of group 14 of thePeriodic Table of the Elements, and optionally sulfur or oxygen, saidmoiety having up to 20 non-hydrogen atoms, and optionally Cp* and Ztogether form a fused ring system;

[0104] X independently each occurrence is an anionic ligand group orneutral Lewis base ligand group having up to 30 non-hydrogen atoms;

[0105] n is 0, 1, 2, 3, or 4 and is 2 less than the valence of M; and

[0106] Y is an anionic or nonanionic ligand group bonded to Z and Mcomprising nitrogen, phosphorus, oxygen or sulfur and having up to 20non-hydrogen atoms, optionally Y and Z together form a fused ringsystem.

[0107] More preferably still, such complexes correspond to the formula:

[0108] wherein:

[0109] R′ each occurrence is independently selected from the groupconsisting of hydrogen, alkyl, aryl, silyl, germyl, cyano, halo andcombinations thereof having up to 20 non-hydrogen atoms;

[0110] X each occurrence independently is selected from the groupconsisting of hydride, halo, alkyl, aryl silyl, germyl, aryloxy, alkoxy,amide, siloxy, neutral Lewis base ligands and combinations thereofhaving up to 20 non-hydrogen atoms;

[0111] Y is —O—, —S—, —NR*—, —PR*—, or a neutral two electron donorligand selected from the group consisting of OR*, SR*, NR*₂ or PR*₂;

[0112] M is as previously defined; and

[0113] Z is SiR*₂, CR*₂, SiR*₂SiR*₂, CR*₂CR*₂, CR*═CR*, CR*₂SiR*₂,GeR*₂, BR*, BR*₂; wherein

[0114] R* each occurrence is independently selected from the groupconsisting of hydrogen, alkyl aryl, silyl, halogenated alkyl,halogenated aryl groups having up to 20 non-hydrogen atoms, and mixturesthereof, or two or more R* groups from Y, Z, or both Y and Z form afused ring system; and n is 1 or 2.

[0115] It should be noted that whereas formula I and the followingformulas indicate a cyclic structure for the catalysts, when Y is aneutral two electron donor ligand, the bond between M and Y is moreaccurately referred to as a coordinate-covalent bond. Also, it should benoted that the complex may exist as a dimer or higher oligomer.

[0116] Further preferably, at least one of R′, Z, or R* is an electrondonating moiety. Thus, highly preferably Y is a nitrogen or phosphoruscontaining group corresponding to the formula —N(R″)— or —P(R″)—,wherein R″ is C₁₋₁₀ alkyl or aryl, i.e., an amido or phosphido group.

[0117] Most highly preferred complex compounds are amidosilane- oramidoalkanediyl-compounds corresponding to the formula:

[0118] wherein:

[0119] M is titanium, zirconium or hafnium, bound in an eta⁵ bondingmode to the cyclopentadienyl group;

[0120] R′ each occurrence is independently selected from the groupconsisting of hydrogen, silyl, alkyl, aryl and combinations thereofhaving up to 10 carbon or silicon atoms;

[0121] E is silicon or carbon;

[0122] X independently each occurrence is hydride, halo, alkyl, aryl,aryloxy or alkoxy of up to 10 carbons;

[0123] m is 1 or 2; and

[0124] n is 1 or 2.

[0125] Examples of the above most highly preferred metal coordinationcompounds include compounds wherein the R′ on the amido group is methyl,ethyl, propyl, butyl, pentyl, hexyl, (including isomers), norbornyl,benzyl, phenyl, etc.; the cyclopentadienyl group is cyclopentadienyl,indenyl, tetrahydroindenyl, fluorenyl, octahydrofluorenyl, etc.; R′ onthe foregoing cyclopentadienyl groups each occurrence is hydrogen,methyl, ethyl, propyl, butyl pentyl, hexyl, (including isomers),norbornyl, benzyl, phenyl, etc.; and X is chloro, bromo, iodo, methyl,ethyl, propyl, butyl, pentyl, hexyl, (including isomers), norbornyl,benzyl, phenyl, etc. Specific compounds include:

[0126](tert-butylamido)(tetramethyl-eta⁵-cyclopentadienyl)-1,2-ethanediylzirconiumdichloride,(tert-butylamido)(tetramethyl-eta⁵-cyclopentadienyl)-1,2-ethanediyltitaniumdichloride,(methylamido)(tetramethyl-eta⁵-cyclopentadienyl)-1,2-ethanediylzirconiumdichloride,(methylamido)(tetramethyl-eta⁵-cyclopentadienyl)-1,2-ethanediyltitaniumdichloride,(ethylamido)(tetramethyl-eta⁵-cyclopentadienyl)-methylenetitaniumdichloro, (tertbutylamido)dibenzyl(tetramethyl-eta⁵-cyclopentadienyl)silanezirconium dibenzyl,(benzylamido)dimethyl-(tetramethyl-eta⁵-cyclopentadienyl)silanetitaniumdichloride,(phenylphosphido)dimethyl(tetramethyl-eta⁵-cyclopentadienyl)silanezirconiumdibenzyl,(tertbutylamido)dimethyl(tetramethyl-eta⁵-cyclopentadienyl)silanetitaniumdimethyl, and the like.

[0127] The complexes may be prepared by contacting a derivative of ametal, M, and a group I metal derivative or Grignard derivative of thecyclopentadienyl compound in a solvent and separating the salt byproductSuitable solvents for use in preparing the metal complexes are aliphaticor aromatic liquids such as cyclohexane, methylcyclohexane, pentane,hexane, heptane, tetrahydrofuran, diethyl ether, benzene, toluene,xylene, ethylbenzene, etc., or mixtures thereof

[0128] In a preferred embodiment, the metal compound is MX_(n+1), i.e.,M is in a lower oxidation state than in the corresponding compound,MX_(n+2) and the oxidation state of M in the desired final complex. Anoninterfering oxidizing agent may thereafter be employed to raise theoxidation state of the metal. The oxidation is accomplished merely bycontacting the reactants utilizing solvents and reaction conditions usedin the preparation of the complex itself. By the term “noninterferingoxidizing agent” is meant a compound having an oxidation potentialsufficient to raise the metal oxidation state without interfering withthe desired complex formation or subsequent polymerization processes. Aparticularly suitable noninterfering oxidizing agent is AgCl or anorganic halide such as methylene chloride. The foregoing techniques aredisclosed in U.S. Ser. Nos. 545,403, filed Jul. 3, 1990 and 702,475,filed May 20, 1991, the teachings of both of which are incorporatedherein by reference.

[0129] Additionally the complexes may be prepared according to theteachings of the copending U.S. application Ser. No. 778,433 entitled:“Preparation of Metal Coordination Complex (I)”, filed in the names ofPeter Nickias and David Wilson, on Oct. 15, 1991 and the copending U.S.application Ser. No. 778,432 entitled: “Preparation of MetalCoordination Complex (II)”, filed in the names of Peter Nickias andDavid Devore, on Oct. 15, 1991, and the patents issuing therefrom, allof which are incorporated herein by reference.

[0130] Suitable cocatalysts for use herein include polymeric oroligomeric aluminoxanes, especially methyl aluminoxane, as well asinert, compatible, noncoordinating, ion forming compounds. So calledmodified methyl aluminoxane (MMAO) is also suitable for use as acocatalyst. One technique for preparing such modified aluminoxane isdisclosed in U.S. Pat. No. 5,041,584. Aluminoxanes can also be made asdisclosed in U.S. Pat. Nos. 5,218,071; 5,086,024, 5,041,585, 5,041,583,5,015,749, 4,960,878 and 4,544,762 all of which are incorporated hereinby reference. Aluminoxanes, including modified methyl aluminoxanes, whenused in the polymerization, are preferably used such that preferablyless than about 20 ppm aluminum, especially less than about 10 ppmaluminum, and more preferably less than about 5 ppm aluminum, fromcatalyst residue remain in the polymer. In order to measure the bulkpolymer properties (e.g. PI or melt fracture), aqueous HCl is used toextract the aluminoxane from the polymer. Preferred cocatalysts,however, are inert, noncoordinating, boron compounds such as thosedescribed in EP 520732 which is incorporated herein by reference.

[0131] Ionic active catalyst species which can be used-to polymerize thepolymers described herein correspond to the formula:

[0132] wherein:

[0133] M is a metal of group 3-10, or the Lanthanide series of thePeriodic Table of the Elements;

[0134] Cp* is a cyclopentadienyl or substituted cyclopentadienyl groupbound in an eta⁵ bonding mode to M;

[0135] Z is a moiety comprising boron, or a member of group 14 of thePeriodic Table of the Elements, and optionally sulfur or oxygen, saidmoiety having up to 20 non-hydrogen atoms, and optionally Cp* and Ztogether form a fused ring system;

[0136] X independently each occurrence is an anionic ligand group orneutral Lewis base ligand group having up to 30 non-hydrogen atoms;

[0137] n is 0, 1, 2, 3, or 4 and is 2 less than the valence of M; and

[0138] A—is a noncoordinating, compatible anion.

[0139] One method of making the ionic catalyst species which can beutilized to make the polymers of the present invention involvecombining:

[0140] a) at least one first component which is a mono(cyclopentadienyl)derivative of a metal of Group 3-10 or the Lanthanide Series of thePeriodic Table of the Elements containing at least one substituent whichwill combine with the cation of a second component (describedhereinafter) which first component is capable of forming a cationformally having a coordination number that is one less than its valence,and

[0141] b) at least one second component which is a salt of a Bronstedacid and a is noncoordinating, compatible anion.

[0142] More particularly, the non-coordinating, compatible anion of theBronsted acid salt may comprise a single coordination complex comprisinga charge-bearing metal or metalloid core, which anion is both bulky andnon-nucleophilic. The recitation “metalloid”, as used herein, includesnon-metals such as boron, phosphorus and the like which exhibitsemi-metallic characteristics.

[0143] Illustrative, but not limiting examples of monocyclopentadienylmetal components (first components) which may be used in the preparationof cationic complexes are derivatives of titanium, zirconium, vanadium,hafnium, chromium, lanthanum, etc. Preferred components are titanium orzirconium compounds. Examples of suitable monocyclopentadienyl metalcompounds are hydrocarbyl-substituted monocyclopentadienyl metalcompounds such as(tert-butylamido)(tetramethyl-eta⁵-cyclopentadienyl)-1,2-ethanediylzirconiumdimethyl,(tert-butylamido)(tetramethyl-eta⁵-cyclopentadienyl)-1,2-ethanediyltitaniumdimethyl,(methylamido)(tetramethyl-eta⁵-cyclopentadienyl)-1,2-ethanediylzirconiumdibenzyl, (methylamido)(tetramethyl-eta⁵-cyclopentadienyl)-1,2-ethanediyltitanium dimethyl(ethylamido)(tetramethyl-eta⁵-cyclopentadienyl)methylenetitaniumdimethyl, (tertbutylamido)dibenzyl(tetramethyl-eta⁵-cyclopentadienyl)silanezirconium dibenzyl, (benzylamido)dimethyl-(tetramethyl-eta⁵-cyclopentadienyl)silanetitanium diphenyl,(phenylphosphido)dimethyl(tetramethyl-O⁵-cyclopentadienyl)silanezirconiumdibenzyl, and the like.

[0144] Such components are readily prepared by combining thecorresponding metal chloride with a dilithium salt of the substitutedcyclopentadienyl group such as a cyclopentadienyl-alkanediyl,cyclopentadienyl-silane amide, or cyclopentadienyl-phosphide compound.The reaction is conducted in an inert liquid such as tetrahydrofuran,C₅₋₁₀ alkanes, toluene, etc. utilizing conventional syntheticprocedures. Additionally, the first components may be prepared byreaction of a group II derivative of the cyclopentadienyl compound in asolvent and separating the salt by-product. Magnesium derivatives of thecyclopentadienyl compounds are preferred. The reaction may be conductedin an inert solvent such as cyclohexane, pentane, tetrahydrofuran,diethyl ether, benzene, toluene, or mixtures of the like. The resultingmetal cyclopentadienyl halide complexes may be alkylated using a varietyof techniques. Generally, the metal cyclopentadienyl alkyl or arylcomplexes may be prepared by alkylation of the metal cyclopentadienylhalide complexes with alkyl or aryl derivatives of group I or group IImetals. Preferred alkylating agents are alkyl lithium and Grignardderivatives using conventional synthetic techniques. The reaction may beconducted in an inert solvent such as cyclohexane, pentane,tetrahydrofuran, diethyl ether, benzene, toluene, or mixtures of thelike. A preferred solvent is a mixture of toluene and tetrahydrofuran.

[0145] Compounds useful as a second component in the preparation of theionic catalysts useful in this invention will comprise a cation, whichis a Bronsted acid capable of donating a proton, and a compatiblenoncoordinating anion Preferred anions are those containing a singlecoordination complex comprising a charge-bearing metal or metalloid corewhich anion is relatively large (bulky), capable of stabilizing theactive catalyst species (the Group 3-10 or Lanthanide Series cation)which is formed when the two components are combined and sufficientlylabile to be displaced by olefinic, diolefinic and acetylenicallyunsaturated substrates or other neutral Lewis bases such as ethers,nitrites and the like. Suitable metals, then, include, but are notlimited to, aluminum, gold, platinum and the like. Suitable metalloidsinclude, but are not limited to, boron, phosphorus silicon and the likeCompounds containing anions which comprise coordination complexescontaining a single metal or metalloid atom are, of course, well knownand many, particularly such compounds containing a single boron atom inthe anion portion, are available commercially. In light of this, saltscontaining anions comprising a coordination complex containing a singleboron atom are preferred.

[0146] Highly preferably, the second component useful in the preparationof the catalysts of this invention may be represented by the followinggeneral formula:

(L−H)+ [A]−

[0147] wherein:

[0148] L is a neutral Lewis base;

[0149] (L−H)+ is a Bronsted acid; and

[0150] [A]− is a compatible, noncoordinating anion.

[0151] More preferably [A]− corresponds to the formula:

[M′Q_(q)]−

[0152] wherein:

[0153] M′ is a metal or metalloid selected from Groups 5-15 of thePeriodic Table of the Elements; and

[0154] Q independently each occurrence is selected from the Groupconsisting of hydride, dialkylamido, halide, alkoxide, aryloxide,hydrocarbyl, and substituted-hydrocarbyl radicals of up to 20 carbonswith the proviso that in not more than one occurrence is Q halide and

[0155] q is one more than the valence of M′.

[0156] Second components comprising boron which are particularly usefulin the preparation of catalysts of this invention may be represented bythe following general formula:

[L−H]+ [BQ_(A)]−

[0157] wherein:

[0158] L is a neutral Lewis base;

[0159] [L−H]+ is a Bronsted acid;

[0160] B is boron in a valence state of 3; and

[0161] Q is as previously defined.

[0162] Illustrative, but not limiting, examples of boron compounds whichmay be used as a second component in the preparation of the improvedcatalysts of this invention are trialkyl-substituted ammonium salts suchas triethylammonium tetraphenylborate, tripropylammoniumtetraphenylborate, tris(n-butyl)ammonium tetraphenylborate,trimethylammonium tetrakis(p-tolyl) borate, tributylammoniumtetrakis(pentafluorophenyl)borate, tripropylammoniumtetrakis(2,4dimethylphenyl)borate, tributylammoniumtetrakis(3,5-dimethylphenyl)borate, triethylammoniumtetrakis(3,5-di-trifluoromethylphenyl)borate and the like. Also suitableare N,N-dialkyl anilinium salts such asN,N-dimethyl-aniliniumtetraphenylborate, N,N-diethylaniliniumtetraphenylborate, N,N-2,4,6pentamethylanilinium tetraphenylborate andthe like; dialkylammonium salts such as di-(i-propyl)ammoniumtetrakis(pentafluorophenyl)borate, dicyclohexylammoniumtetraphenylborate and the like; and triaryl phosphonium salts such astriphenylphosphonium tetraphenylborate, tri(methylphenyl)phosphoniumtetrakis-pentafluorophenylborate, tri(dimethylphenyl)phosphoniumtetraphenylborate and the like.

[0163] Preferred ionic catalysts are those having a limiting chargeseparated structure corresponding to the formula:

[0164] wherein:

[0165] M is a metal of group 3-10, or the Lanthanide series of thePeriodic Table of the Elements;

[0166] Cp* is a cyclopentadienyl or substituted cyclopentadienyl groupbound in an eta⁵ bonding mode to M;

[0167] Z is a moiety comprising boron, or a member of group 14 of thePeriodic Table of the Elements, and optionally sulfur or oxygen, saidmoiety having up to 20 non-hydrogen atoms, and optionally Cp* and Ztogether form a fused ring system;

[0168] X independently each occurrence is an anionic ligand group orneutral Lewis base ligand group having up to 30 non-hydrogen atoms;

[0169] n is 0, 1, 2, 3, or 4 and is 2 less than the valence of M; and

[0170] XA*— is —XB(C₆F₅)₃.

[0171] This class of cationic complexes may be conveniently prepared bycontacting a metal compound corresponding to the formula

[0172] wherein:

[0173] Cp*, M, and n are as previously defined,

[0174] with tris(pentafluorophenyl)borane cocatalyst under conditions tocause abstraction of X and formation of the anion —XB(C₆F₅)₃.

[0175] Preferably X in the foregoing ionic catalyst is

[0176] C₁-C₁₀ hydrocarbyl, most preferably methyl.

[0177] The preceding formula is referred to as the limiting, chargeseparated structure. However, it is to be understood that, particularlyin solid form, the catalyst may not be fully charge separated. That is,the X group may retain a partial covalent bond to the metal atom, M.Thus, the catalysts may be alternately depicted as possessing theformula:

[0178] The catalysts are preferably prepared by contacting thederivative of a Group 4 or Lanthanide metal with thetris(pentafluorophenyl)borane in an inert diluent such as an organicliquid.

[0179] Tris(pentafluorphenyl)borane is a commonly available Lewis acidthat may be readly prepared according to known techniques. The compoundis disclosed in Marks, et al. J. Am. Chem. Soc. 1991, 113, 3623-3625 foruse in alkyl abstraction of zirconocenes.

[0180] All reference to the Periodic Table of the Elements herein shallrefer to the Periodic Table of the Elements, published and copyrightedby CRC Press, Inc., 1989. Also, any reference to a Group or Groups shallbe to the Group or Groups as reflected in this Periodic Table of theElements using the IUPAC system for numbering groups.

[0181] It is believed that in the constrained geometry catalysts usedherein the metal atom is forced to greater exposure of the active metalsite because one or more substituents on the single cyclopentadienyl orsubstituted metal is both bonded to an adjacent covalent moiety and heldin association with the cyclopentadienyl group through an eta5 or otherpi-bonding interaction. It is understood that each respective bondbetween the metal atom and the constituent atoms of the cyclopentadienylor substituted cyclopentadienyl group need not be equivalent. That is,the metal may be symmetrically or unsymmetrically pi-bound to thecyclopentadienyl or substituted cyclopentadienyl group.

[0182] The geometry of the active metal site is further defined asfollows. The centroid of the cyclopentadienyl or substitutedcyclopentadienyl group may be defined as the average of the respectiveX, Y, and Z coordinates of the atomic centers forming thecyclopentadienyl or substituted cyclopentadienyl group. The angle,theta, formed at the metal center between the centroid of thecyclopentadienyl or substituted cyclopentadienyl group and each otherligand of the metal complex may be easily calculated by standardtechniques of single crystal X-ray diffraction. Each of these angles mayincrease or decrease depending on the molecular structure of theconstrained geometry metal complex. Those complexes wherein one or moreof the angles, theta, is less than in a similar, comparative complexdiffering only in the fact that the constrain inducing substituent isreplaced by hydrogen, have constrained geometry for purposes of thepresent invention Preferably one or more of the above angles, theta,decrease by at least 5 percent, more preferably 7.5 percent, compared tothe comparative complex. Highly preferably, the average value of allbond angles, theta, is also less than in the comparative complex.

[0183] Preferably, monocyclopentadienyl metal coordination complexes ofgroup 4 or lanthanide metals according to the present invention haveconstrained geometry such that the smallest angle, theta, between thecentroid of the Cp* group and the Y substituent, is less than 115degrees, more preferably less than 110 degrees, most preferably lessthan 105 degrees, and especially less than 100 degrees.

[0184] Other compounds which are useful in the catalyst compositions ofthis invention, especially compounds containing other Group 4 orlanthanide metals, will, of course, be apparent to those skilled in theart.

[0185] Polymerization

[0186] The improved melt elasticity and processibility of thesubstantially linear polymers according to the present invention result,it is believed, from their method of production. The polymers may beproduced via a continuous (as opposed to a batch) controlledpolymerization process using at least one reactor (e.g., as disclosed inWO 93/07187, WO 93/07188, and WO 93/07189, the disclosures of each ofwhich is incorporated herein by reference), but can also be producedusing multiple reactors (e.g., using a multiple reactor configuration asdescribed in U.S. Pat. No. 3,914,342, the disclosure of which isincorporated herein by reference) at a polymerization temperature andpressure sufficient to produce the interpolymers having the desiredproperties.

[0187] While not wishing to be bound by any particular theory, theinventors believe that long chain branches are formed in their novelpolymers according to the following sequence:

[0188] Propagation Step

R—(C₂H₄)+Catalyst—R—C₂H₄-Catalyst

[0189] Termination Step

R—C₂H₄-Catalyst—R—CH═CH₂ (beta-hydride elimination)

[0190] Copolymerization

R—CH₂—CH₂—CHR′—-CH₂-Catalyst—R—CH₂—CH₂—CHR′—CH₂-Catalyst

[0191] Continued Polymerization

R—CH₂—CH₂—CHR′—CH₂-Catalyst+(C₂H₄)_(x)—R—CHR′(CH₂CH₂)_(x)-Catalyst

[0192] Termination Step

R—CHR′(CH₂CH₂)_(x)-Catalyst+Heat—R—CHR′R″CH═CH₂+H-Catalyst   1)

R—CHR′(CH₂CH₂)_(x)-Catalyst+H₂—R—CHR′R″+H-Catalyst   2)

[0193] wherein:

[0194] R=growing polymer chain

[0195] R′=long chain branch (LCB), and

[0196] R″=growing polymer chain after insertion of R″.

[0197] In polymerizing ethylene and ethylene/alpha-olefin copolymers, abatch reactor process typically operates at an ethylene concentrationfrom about 6.7 to about 12.5 percent by weight of the reactor contentsand have a polymer concentration generally less than about 5 percent byweight of the reactor contents, dependent upon the ethylene solubility,which is a function of reactor diluent, temperature and pressure. Theinitital polymer concentration is zero and increases over time as thereaction proceeds such that the highest polymer concentration occurs atthe end of the reaction, the point at which the catalyst is spent. Mostof the polymer is made during the initial minutes of the polymerization.

[0198] According to one embodiment of the present process, the polymersare produced in a continuous process operated at a steady state (i.e.the reactants are fed to the reactor at a rate in substantially inbalance with the rate that product is removed from the reactor such thatthe reaction mass in the reactor is relatively constant in volume andcomposition), as opposed to a batch process. Preferably, thepolymerization temperature of the continuous process is from about 20 C.to about 250 C., using constrained geometry catalyst technology. If anarrow molecular weight distribution polymer (M_(w)/M_(n) of from about1.5 to about 2.5) having a higher I₁₀/I₂ ratio (e.g. I₁₀/I₂ of 7 ormore, preferably at least 8, especially at least 9 and as high as about20 or more) is desired, the ethylene concentration in the reactor ispreferably not more than about 8 percent by weight of the reactorcontents, especially not more than about 6 percent by weight of thereactor contents, and most especially not more than about 4 percent byweight of the reactor contents, and as low as about 0.75 percent byweight of the reactor contents. Preferably, the polymerization isperformed in a solution polymerization process. Generally, manipulationof I₁₀/I₂ while holding M_(w)/M_(n) relatively low for producing thenovel polymers described herein is a function of reactor temperatureand/or ethylene concentration. Surprisingly, reduced ethyleneconcentration and higher temperature generally produces higher I₁₀/I₂.Generally, as the percent of ethylene is converted into polymer, theethylene concentration in the reactor decreases and the polymerconcentration increases. For the novel substantially linearethylene/alpha-olefin copolymers and substantially linear ethylenehomopolymers claimed herein, the polymer concentration for a continuoussolution polymerization process is preferably above about 5 weightpercent of the reactor contents, especially above about 15 weightpercent of the reactor contents, and as high as about 40 weight percentof the reactor contents. Typically greater than 70 percent, preferablygreater than 80 percent and more preferably greater than 90 percent, ofthe ethylene is converted to polymer.

[0199] The substantially linear polymers of the present invention can beethylene homopolymers, or they can be interpolymers of ethylene with atleast one C₃-C₂₀ alpha-olefin and/or C₄-C₁₈ diolefins. The substantiallylinear polymers of the present invention can also be interpolymers ofethylene with at least one of the above C₃-C₂₀ alpha-olefins and/ordiolefins in combination with other unsaturated monomers.

[0200] Monomers usefully copolymerized or interpolymerized with ethyleneaccording to the present invention include, for example, ethylenicallyunsaturated monomers, conjugated or nonconjugated dienes, polyenes, etc.Preferred comonomers include the C₃-C₁₀ alpha-olefins especiallypropene, isobutylene, 1-butene, 1-hexene, 4-methyl-1-pentene, and1-octene. Other preferred monomers include styrene, halo- or alkylsubstituted styrenes, vinylbenzocyclobutene, 1,4-hexadiene, andnaphthenics (e.g., cyclo-pentene, cyclo-hexene and cyclo-octene).

[0201] Other unsaturated monomers usefully copolymerized according tothe present invention include, for example, ethylenically unsaturatedmonomers, conjugated or nonconjugated dienes, polyenes, etc. Preferredcomonomers include the C₃-C₁₀ alpha-olefins especially propene.isobutylene, 1-butene, 1-hexene, 4methyl-1-pentene, and 1-octene. Otherpreferred comonomers include styrene, halo- or alkyl substitutedstyrenes, vinylbenzocyclobutene, 1,4hexadiene, and naphthenics (e.g.,cyclopentene, cyclohexene and cyclooctene).

[0202] The polymerization conditions for manufacturing the polymers ofthe present invention are generally those useful in the solutionpolymerization process, although the application of the presentinvention is not limited thereto. Slurry and gas phase polymerizationprocesses are also believed to be useful, provided the proper catalystsand polymerization conditions are employed.

[0203] Multiple reactor polymerization processes are also useful in thepresent invention, such as those disclosed in U.S. Pat. No. 3,914,342.The multiple reactors can be operated in series or in parallel, with atleast one constrained geometry catalyst employed in at least one of thereactors.

[0204] In general, the continuous polymerization according to thepresent invention may be accomplished at conditions well known in theprior art for Ziegler-Natta or Kaminsky-Sinn type polymerizationreactions, that is, temperatures from 0 to 250 C. and pressures fromatmospheric to 1000 atmospheres (100 MPa). Suspension, solution, slurry,gas phase or other process conditions may be employed if desired. Asupport may be employed, but preferably the catalysts are used in ahomogeneous (i.e., soluble) manner. It will, of course, be appreciatedthat the active catalyst system form in situ if the catalyst and thecocatalyst components thereof are added directly to the polymerizationprocess and a suitable solvent or diluent, including condensed monomer,is used in said polymerization process. It is, however, preferred toform the active catalyst in a separate step in a suitable solvent priorto adding the same to the polymerization mixture.

[0205] The polymerization conditions for manufacturing the polymers ofthe present invention are generally those useful in the solutionpolymerization process, although the application of the presentinvention is not limited thereto. Gas phase polymerization processes arealso believed to be useful, provided the proper catalysts andpolymerization conditions are employed.

[0206] Fabricated articles made from the novel ethylene polymers may beprepared using all of the conventional polyethylene processingtechniques. Useful articles include films (e.g., cast, blown andextrusion coated), fibers (e.g., staple fibers (including use of a novelethylene polymer disclosed herein as at least one component comprisingat least a portion of the fiber's surface), spunbond fibers or meltblown fibers (using, e.g., systems as disclosed in U.S. Pat. Nos.4,340,563, 4,663,220, 4,668,566, or 4,322,027), and gel spun fibers(e.g., the system disclosed in U.S. Pat. No. 4,413,110)), both woven andnonwoven fabrics (e.g., spunlaced fabrics disclosed in U.S. Pat. No.3,485,706) or structures made from such fibers (including, e.g., blendsof these fibers with other fibers, e.g., PET or cotton) and moldedarticles (e.g., made using an injection molding process, a blow moldingprocess or a rotomolding process). The new polymers described herein arealso useful for wire and cable coating operations, impact modification,especially at low temperatures, of thermoplastic olefins (e.g.,polypropylene), as well as in sheet extrusion for vacuum formingoperations, closed cell and open cell foams including radiation andchemically crosslinked foams and foam structures), and adhesives. All ofthe preceding patents are incorporated herein by reference.

[0207] Useful compositions are also suitably prepared comprising thesubstantially linear polymers of the present invention and at least oneother natural or synthetic polymer. Preferred other polymers includethermoplastics such as styrene-butadiene block copolymers, polystyrene(including high impact polystyrene), ethylene vinyl acetate copolymers,ethylene acrylic acid copolymers, other olefin copolymers (especiallypolyethylene copolymers) and homopolymers (e.g., those polyethylenecopolymers and homopolymers made using conventional heterogeneouscatalysts). Examples of such heterogeneous polyethylene polymers andcopolymers include polymers made by the process of U.S. Pat. No.4,076,698 (incorporated herein by reference), other linear orsubstantially linear polymers of the present invention, and mixturesthereof. Other substantially linear polymers of the present inventionand conventional heterogeneously branched HDPE and/or heterogeneouslybranched LLDPE are preferred for use in the thermoplastic compositions.

[0208] The compositions comprising the substantially linear ethylenepolymers are formed by any convenient method, including dry blending theindividual components and subsequently melt mixing, either directly inthe extruder used to make the finished article (e.g., film), or bypre-melt mixing in a separate extruder. The polyethylene compositionsmay also be prepared by multiple reactor polymerization techniques. Forexample, one reactor may polymerize the constrained geometry catalyzedpolyethylene and another reactor polymerize the heterogeneous catalyzedpolyethylene, either in series or in parallel operation.

[0209] Compositions comprising the ethylene polymers can also be formedinto fabricated articles such as those previously mentioned usingconventional polyethylene processing techniques which are well known tothose skilled in the art of polyethylene processing.

[0210] For examples described herein, unless otherwise stipulated, allprocedures were performed under an inert atmosphere of nitrogen orargon. Solvent choices were often optional, for example, in most caseseither pentane or 30-60 petroleum ether can be interchanged. Amines,silanes, lithium reagents, and Grignard reagents were purchased fromAldrich Chemical Company. Published methods for preparingtetramethylcyclopentadiene (C₅Me₄H₂) and lithiumtetramethylcyclopentadienide (Li(C₅Me₄H)) include C. M. Fendrick et al.Organometallics, 3, 819 ( 1984). Lithiated substituted cyclopentadienylcompounds may be typically prepared from the correspondingcyclopentadiene and a lithium reagent such as n-butyl lithium Titaniumtrichloride (TiCl₃) was purchased from Aldrich Chemical Company. Thetetrahydrofuran adduct of titanium trichloride, TiCl₃(THF)₃, wasprepared by refluxing TiCl₃ in THF overnight, cooling, and isolating theblue solid product, according to the procedure of L. E. Manzer, Inorg.Syn., 21, 135 (1982).

EXAMPLES 1-4

[0211] The metal complex solution for Example 1 is prepared as follows:

[0212] Part 1: Prep of Li(C₅Me₄H)

[0213] In the drybox, a 3L 3-necked flask was charged with 18.34 g ofC₅Me₄H₂, 800 mL of pentane, and 500 mL of ether. The flask was toppedwith a reflux condenser, a mechanical stirrer, and a constant additionfunnel container 63 mL of 2.5 M n-BuLi in hexane. The BuLi was addeddropwise over several hours. A very thick precipitate formed; approx.1000 mL of additional pentane had to be added over the course of thereaction to allow stirring to continue. After the addition was complete,the mixture was stirred overnight. The next day, the material wasfiltered, and the solid was thoroughly washed with pentane and thendried under reduced pressure. 14.89 g of Li(C₅Me₄H) was obtained (78percent).

[0214] Part 2: Prep of C₅Me₄HSiMe₂Cl

[0215] In the drybox 30.0 g of Li(C₅Me₄H) was placed in a 500 mL Schlenkflask with 250 mL of THF and a large magnetic stir bar. A syringe wascharged with 30 mL of Me₂SiCl₂ and the flask and syringe were removedfrom the drybox. On the Schlenk line under a flow of argon, the flaskwas cooled to −78 C., and the Me₂SiCl₂ added in one rapid addition. Thereaction was allowed to slowly warm to room temperature and stirredovernight. The next morning the volatile materials were removed underreduced pressure, and the flask was taken into the drybox. The oilymaterial was extracted with pentane,-filtered, and the pentane wasremoved under reduced pressure to leave the C₅Me₄HSiMe₂Cl as a clearyellow liquid (46.83 g; 92.9 percent).

[0216] Part 3: Prep of C₅Me₄HSiMe₂NH^(t)Bu

[0217] In the drybox, a 3-necked 2 L flask was charged with 37.4 g oft-butylamine and 210 mL of THF. C₅Me₄HSiMe₂Cl (25.47 g) was slowlydripped into the solution over 3-4 hours. The solution turned cloudy andyellow. The mixture was stirred overnight and the volatile materialsremoved under reduced pressure. The residue was extracted with diethylether, the solution was filtered, and the ether removed under reducedpressure to leave the C₅Me₄HSiMe₂NH^(t)Bu as a clear yellow liquid(26.96 g; 90.8 percent).

[0218] Part 4: Prep of [MgCl]₂[Me₄C₅SiMe₂N^(t)Bu](THF)_(x)

[0219] In the drybox, 14.0 mL of 2.0 M isopropylmagnesium chloride inether was syringed into a 250 mL flask. The ether was removed underreduced pressure to leave a colorless oil. 50 mL of a 4:1 (by volume)toluene:THF mixture was added followed by 3.50 g of Me₄HC₅SiMe₂NH^(t)Bu.The solution was heated to reflux. After refluxing for 2 days, thesolution was cooled and the volatile materials removed under reducedpressure. The white solid residue was slurried in pentane and filteredto leave a white powder, which was washed with pentane and dried underreduced pressure. The white powder was identified as[MgCl]₂[Me₄C₅SiMe₂N^(t)Bu](THF)_(x) (yield: 6.7 g).

[0220] Part 5: Prep of [C₅Me₄(SiMe₂N^(t)Bu)]TiCl₂

[0221] In the drybox, 0.50 g of TiCl₃(THF)₃ was suspended in 10 mL ofTHF. 0.69 g of solid [MgCl]₂[Me₄C₅SiMe₂N^(t)Bu](THF)_(x) was added,resulting in a color change from pale blue to in deep purple. After 15minutes, 0.35 g of AgCl was added to the solution. The color immediatelybegan to lighten to a pale green/yellow. After 1.5 hours, the THF wasremoved under reduced pressure to leave a yellow-green solid. Toluene(20 mL) was added, the solution was filtered, and the toluene wasremoved under reduced pressure to leave a yellow-green solid, 0.51 g(quantitative yield) identified by 1H NMR as [C₅Me₄(SiMe₂N^(t)Bu)]TiCl₂.

[0222] Part 6: Preparation of [C₅Me₄(SiMe₂N^(t)Bu)]TiMe₂

[0223] In an inert atmosphere glove box, 9.031 g of[C₅Me₄(Me₂SiN^(t)Bu)]TiCl₂ is charged into a 250 ml flask and dissolvedinto 100 ml of THF. This solution is cooled to about −25 C. by placementin the glove box freezer for 15 minutes. To the cooled solution is added35 ml of a 1.4 M MeMgBr solution in toluene/THF (75/25). The reactionmixture is stirred for 20 to 25 minutes followed by removal of thesolvent under vacuum. The resulting solid is dried under vacuum forseveral hours. The product is extracted with pentane (4×50 ml) andfiltered. The filtrate is combined and the pentane removed under vacuumgiving the catalyst as a straw yellow solid.

[0224] The metal complex, [C₅Me₄(SiMe₂N^(t)Bu)]TiMe₂, solution forExamples 2 and 3 is prepared as follows:

[0225] In an inert atmosphere glove box 10.6769 g of a tetrahydrofuranadduct of titanium trichloride, TiCl₃(THF)₃, is loaded into a 1 L flaskand slurried into 300 ml of THF. To this slurry, at room temperature, isadded 17.402 g of [MgCl]₂ [N^(t)BuSiMe₂C₅Me₄] (THF)_(x) as a solid Anadditional 200 ml of THF is used to help wash this solid into thereaction flask. This addition resulted in an immediate reaction giving adeep purple solution. After stirring for 5 minutes 9.23 ml of a 1.56 Msolution of CH₂Cl₂ in THF is added giving a quick color change to darkyellow. This stage of the reaction is allowed to stir for about 20 to 30minutes. Next, 61.8 ml of a 1.4 M MeMgBr solution in toluene/THF(75/25)is added via syringe. After about 20 to 30 minutes stirring time thesolvent is removed under vacuum and the solid dried. The product isextracted with pentane (8×50 ml) and filtered. The filtrate,is combinedand the pentane removed under vacuum giving the metal complex as a tansolid.

[0226] The metal complex, [C₅Me₄(SiMe₂N^(t)Bu)]TiMe₂, solution forExample 4 is prepared as follows:

[0227] In an inert atmosphere glove box 4.8108 g of TiCl₃(THF)₃ isplaced in a 500 ml flask and slurried into 130 ml of THF. In a separateflask 8.000 g of [MgCl]₂[N^(t)BuSiMe₂C₅Me₄](THF)_(x) is dissolved into150 ml of THF. These flasks are removed from the glove box and attachedto a vacuum line and the contents cooled to −30 C. The THF solution of[MgCl]₂[N^(t)BuSiMe₂C₅Me₄](THF)_(x) is transferred (over a 15 minuteperiod) via cannula to the flask containing the TiCl₃(THF)₃ slurry. Thisreaction is allowed to stir for 1.5 hours over which time thetemperature warmed to 0 C. and the solution color turned deep purple Thereaction mixture is cooled back to −30 C. and 4.16 ml of a 1.56 M CH₂Cl₂solution in THF is added. This stage of the reaction is stirred for anadditional 1.5 hours and the temperature warmed to −10 C. Next, thereaction mixture is again cooled to −40 C. and 27.81 ml of a 1.4 MMeMgBr solution in toluene/THF (75/25) was added via syringe and thereaction is now allowed to warm slowly to room temperature over 3 hours.After this time the solvent is removed under vacuum and the solid dried.At this point the reaction flask is brought back into the glove boxwhere the product is extracted with pentane (4×50 ml) and filtered. Thefiltrate is combined and the pentane removed under vacuum giving thecatalyst as a tan solid. The metal complex is then dissolved into amixture of C₈-C₁₀ saturated hydrocarbons (e.g., Isopar™ E, made byExxon) and ready for use in polymerization.

[0228] Polymerization

[0229] The polymer products of Examples 1-4 are produced in a solutionpolymerization process using a continuously stirred reactor. Additives(e.g., antioxidants, pigments, etc.) can be incorporated into theinterpolymer products either during the pelletization step or aftermanufacture, with a subsequent re-extrusion. Examples 1-4 are eachstabilized with 1250 ppm calcium stearate, 200 ppm Irganox 1010, and1600 ppm Irgafos 168. Irgafos™ 168 is a phosphite stabilizer andIrganox™ 1010 is a hindered polyphenol stabilizer (e.g., tetrakis[methylene 3-(3,5-ditertbutyl-4-hydroxyphenylpropionate)]methane. Bothare trademarks of and made by Ciba-Geigy Corporation. A representativeschematic for the polymerization process is shown in FIG. 1.

[0230] The ethylene (4) and the hydrogen are combined into one stream(15) before being introduced into the diluent mixture (3). Typically,the diluent mixture comprises a mixture of C₈-C₁₀ saturated hydrocarbons(1), (e.g., Isopar™E, made by Exxon) and the comonomer(s) (2). ForExample 1, the comonomer is 1-octene. The reactor feed mixture (6) iscontinuously injected into the reactor (9). The metal complex (7) andthe cocatalyst (8) (the cocatalyst is tris(pentafluorophenyl)borane forExamples 1-4 herein which forms the ionic catalyst in situ) are combinedinto a single stream and also continuously injected into the reactor.Sufficient residence time is allowed for the metal complex andcocatalyst to react to the desired extent for use in the polymerizationreactions, at least about 10 seconds. For the polymerization reactionsof Examples 1-4, the reactor pressure is held constant at about 490psig. Ethylene content of the reactor, after reaching steady state, ismaintained below about 8 percent.

[0231] After polymerization, the reactor exit stream (14) is introducedinto a separator (10) where the molten polymer is separated from theunreacted comonomer(s), unreacted ethylene, unreacted hydrogen, anddiluent mixture stream (13). The molten polymer is subsequently strandchopped or pelletized and, after being cooled in a water bath orpelletizer (11), the solid pellets are collected (12). Table 1 describesthe polymerization conditions and the resultant polymer properties:TABLE I Example 1* 2 3 4 Ethylene feed rate (lbs/hour) 3.2 3.8 3.8 3.8Comonomer/Total Olefin 12.3 0 0 0 ratio* (mole percent)Hydrogen/ethylene ratio (mole 0.054 0.072 0.083 0.019 percent)Diluent/ethylene ratio (weight 9.5 7.4 8.7 8.7 basis) Metal complexconc. 0.00025 0.0005 0.001 0.001 (molar) Metal complex flow rate 5.9 1.72.4 4.8 (ml/min) Cocatalyst conc. 0.001 0.001 0.002 0.002 (molar)Cocatalyst flow rate (ml/min) 2.9 1.3 6 11.9 Reactor temp (EC) 114 160160 200 Polymer concentration (wt %) 7.1 8.4 9.5 8.4 in the reactor exitstream Comonomer concentration (wt 3.8 0 0 0 %) in the reactor exitstream Ethylene conc. in the reactor 2.65 3.59 0.86 1.98 exit stream(weight percent) Product I₂ 1.22 0.96 1.18 0.25 (g/10 minutes) Productdensity 0.903 0.954 0.954 0.953 (g/cm³) Product I₁₀/I₂ 6.5 7.4 11.8 16.1Single DSC Melting Peak (C) 97 132 131 132 Product M_(w) 95,400 93,80071,600 105,800 Product M_(n) 50,000 48,200 34,200  51,100 ProductM_(w)/M_(n) 1.91 1.95 2.09 2.07 Ethylene Conversion (%) 71 70 92 81LCB/Coain N.M.** — 0.53 0.66 LCB/10,000 Carbons N.M.** — 2.2 1.8Aluminium Residue (ppm) 0 0 0 0

[0232] The ¹³C NMR spectrum of Example 3 (ethylene homopolymer) showspeaks which can be assigned to the alpha,delta⁺, beta,delta⁺ and methinecarbons associated with a long chain branch. Long chain branching isdetermined using the method of Randall described earlier in thisdisclosure, wherein he states that “Detection of these resonances inhigh-density polyethylenes where no 1-olefins were added during thepolymerization should be strongly indicative of the presence of longchain branching.” Using the equation 141 from Randall (p. 292):

Branches per 10,000 carbons=[1/3(alpha)/T _(T∝)]×10⁴,

[0233] wherein alpha=the average intensity of a carbon from a branch(alpha,delta⁺) carbon and T_(T∝)=the total carbon intensity. The numberof long chain branches in this sample is determined to be 3.4 per 10,000total carbon atoms, or 0.34 long chain branches/1000 total carbon atomsusing 300 MHz ¹³C NMR, and 2.2 per 10,000 total carbon atoms, or 0.22long chain branches/1000 total carbon atoms using a 600 MHz ¹³C NMR.

EXAMPLES 5, 6 AND COMPARATIVE EXAMPLES 7-9

[0234] Examples 5, 6 and Comparison Examples 7-9 with the same meltindex are tested for rheology Comparison. Examples 5 and 6 are thesubstantially linear ethylene/1-octene copolymers produced by theconstrained geometry catalyst technology, as described in Example 1,with the exception that lower ethylene concentrations were used forExamples 5 and 6 providing for higher I₁₀/I₂ ratios and consequentlymore long chain branching than Example 1. Examples 5 and 6 arestabilized as Examples 1-4. Comparison Examples 7, 8 and 9 areconventional heterogeneous Ziegler polymerization blown film resinsDowlex™ 2045A, Attane™ 4201, and Attane™ 4403, respectively, all ofwhich are ethylene/1-octene copolymers made by The Dow Chemical Company.

[0235] Comparative Example 7 is stablized with 200 ppm Irganox™ 1010,and 1600 ppm Irgafos™ 168 while Comparative Examples 8 and 9 arestablized with 200 ppm Irganox™ 1010 and 800 ppm PEPQ™. PEPQ™ is atrademark of Sandoz Chemical, the primary ingredient of which isbelieved to betetrakis-(2,4-di-tertbutyl-phenyl)4,4′biphenylphosphonite. A comparisonof the physical properties of each Example and Comparative Example islisted in Table II. TABLE II Comparative Comparative ComparativeProperty Ex. 5 Ex. 6 Example 7 Example 8 Example 9 I₂ 1 1 1 1 0.76 (g/10minutes) Density 0.92 0.902 0.92 0.912 0.905 (g/cm³) I₁₀/I₂ 9.45 7.617.8-8  8.2 8.7 Product M_(w) 73.800 96.900 124.600 122.500 135.300Product M_(n) 37.400 46.400 34.300 32.500 31.900 Product M_(w)/M_(n)1.97 2.09 3.5-3.8 3.8 3.8-4.2 DSC Melt Peak(s) 111 95 114, 118, 122 100,116, 121 96, 116, 121 (C)

[0236] Surprisingly, even though the molecular weight distribution ofExamples 5 and 6 is narrow (i.e., M_(w)/M_(n) is low), the I₁₀/C₂ valuesare comparable or higher in comparison with Comparative Examples 7-9. Acomparison of the relationship between I₁₀/I₂ vs. M_(w)/M_(n) for someof the novel polymers described herein and conventional heterogeneousZiegler polymers is given in FIG. 2. The I₁₀/I₂ value for the novelpolymers of the present invention is essentially independent of themolecular weight distribution, M_(w)/M_(n) which is not true forconventional Ziegler polymerized resins.

[0237] Example 5 and Comparative Example 7 with similar melt index anddensity (Table II) are also extruded via a Gas Extrusion Rheometer (GER)at 190 C. using a 0.0296″ diameter, 20:1 L/D die. The processing index(P.I.) is measured at an apparent shear stress of 2.15×10⁶ dyne/cm² asdescribed previously. The onset of gross melt fracture can easily beidentified from the shear stress vs. shear rate plot shown in FIG. 3where a sudden jump of shear rate occurs. A comparison of the shearstresses and corresponding shear rates before the onset of gross meltfracture is listed in Table III. It is particularly interesting that thePI of Example 5 is more than 20 percent lower than the PI of ComparativeExample 7 and that the onset of melt fracture or sharkskin for Example 5is also at a significantly higher shear stress and shear rate incomparison with the Comparative Example 7. Furthermore, the Melt Tension(MT) as well as Elastic Modulus of Example 5 are higher than that ofComparative Example 7.

[0238] Note that each of the Comparative Examples 7-9 has three distinctmelting peaks as measured by DSC, which is evidence of theirheterogeneous branching distribution. In contrast, the polymers ofExamples 5 and 6 have a single melting peak as measured by DSC betweenthe temperatures of −30 and 150 C. which is evidence of the homogeneityof the polymers branching distribution. Furthermore, the single meltingpeaks of Examples 5 and 6 indicate that each polymer is not a “blend”unlike the polymers disclosed in U.S. Pat. No. 5,218,071. TABLE IIIComparative Property Example 5 Example 7 I₂ (g/10 minutes) 1 1 I₁₀/I₂9.45 7.8-8 PI (kpoise) 11 15 Melt tension (gms) 1.89 1.21 Elasticmodulus at 0.1 2425 882.6 rad/sec (dynes/cm²) OGMF*, critical shearrate >1556 936 (1/sec) (not observed) OGMF*, critical shear stress≧0.452 0.366 (MPa) (not observed) OSMF**, critical shear rate >1566about 628  (1/sec) (not observed) OSMF**, critical shear stress ≧0.452about 0.25 (MPa) (not observed)

[0239] Example 6 and Comparison Example 9 have similar melt index anddensity, but Example 6 has lower I₁₀/I₂ (Table IV). These polymers areextruded via a Gas Extrusion Rheometer (GER) at 190 C. using a 0.0296inch diameter, 20:1 L/D die. The processing index (PI) is measured at anapparent shear stress of 2.15×10⁶ dyne/cm² as described previously.TABLE IV Comparative Property Example 6 Example 9 I₂ 1 0.76 (g/10minutes) I₁₀/I₂ 7.61 8.7 PI (kpoise) 14 15 Melt tension (gms) 1.46 1.39Elastic modulus at 0.1 1481 1921 rad/sec (dynes/cm²) OGMF*, criticalshear rate 1186 652 (1/sec) OGMF* critical shear stress 0.431 0.323(MPa) OSMF**, critical shear rate about 764 about 402 (1/sec) OSMF**,critical shear stress 0.366 0.280 (MPa)

[0240] The onset of gross melt fracture can easily be identified fromthe shear stress vs. shear rate plot shown in FIG. 4 where a suddenincrease of shear rate occurs at an apparent shear stress of about3.23×10⁶ dyne/cm² (0.323 MPa). A comparison of the critical shearstresses and corresponding critical shear rates at the onset of grossmelt fracture is listed in Table IV. The PI of Example 6 is surprisinglyabout the same as Comparative Example 9, even though the I₁₀/I₂ is lowerfor Example 6. The onset of melt fracture or sharkskin for Example 6 isalso at a significantly higher shear stress and shear rate in comparisonwith the Comparative Example 9. Furthermore, it is also unexpected thatthe Melt Tension (MT) of Example 6 is higher than that of ComparativeExample 9, even though the melt index for Example 6 is slightly higherand the I₁₀/I₂ is slightly lower than that of Comparative Example 9.

COMPARATIVE EXAMPLES 10-19

[0241] Batch ethylene/1-octene polymerizations were conducted under thefollowing conditions:

[0242] Preparation of [HNEt₃]+[MeB(C₆F₅)₃]

[0243] A 100 ml flask was charged with 1.00 gram oftris(pentafluorophenyl)boron (1.95 mmol) and 70 ml of anhydrous pentane.After dissolution, 1.5 ml of MeLi (1.4 M in diethyl ether, 2.1 mmol,1.07 equiv) was added at 25 C. via syringe. A milky white mixture formedimmediately and, after several minutes, two phases formed. The mixturewas stirred for 15 hr and then the upper layer decanted. The viscouslower layer was washed twice with 30 ml of pentane and concentrated invacuo for 2 hours to give a clear, colorless, viscous oil. Undernitrogen, the oil was quenched with a 40 ml of an aqueous 0.5 M HNEt₃Clsolution (20 mmol, 10 equiv) which had previously been cooled to 0 C. Awhite, gooey precipitate formed instantly. After two minutes, the solidwas collected by filtration and washed twice with 20 ml of 0.5 M HNEt₃Clsolution followed by two washings with distilled water. The solid wasdehydrated under high vacuum at 25 C. for 15 hours to give a powderywhite solid (0.77 grams, 5 63%) which was identified as the desiredtriethylammonium tris(pentafluorophenyl)methylborate salt.

[0244] Preparation of [HNEt₃]+[(allyl)B(C₆F₅)3]

[0245] A 100 ml flask was charged with 1.00 gram oftris(pentafluorophenyl)boron (1.95 mmol) and 40 ml of anhydrous pentane.After dissolution, 2.05 ml of (allyl)MgBr (1.0 M in diethyl ether, 2.05mmol, 1.05 equiv) was added at 25 C. via syringe. A cloudy white mixtureformed immediately and, after several minutes, two phases formed. Themixture was stirred for 15 hr and then the upper layer decanted. Theviscous lower layer was washed twice with 30 ml of pentane andconcentrated in vacuo for 2 hours to give a clear, colorless, viscousoil. Under nitrogen, the oil was quenched with a 40 ml of an aqueous 0.5M HNEt₃Cl solution (20 mmol, 10 equiv) which had previously been cooledto 0 C. A gooey, white precipitate formed after several minutes. Thesolid was collected by filtration and washed twice with 20 ml of 0.5 MHNEt₃Cl solution followed by two washings with distilled water. Thesolid was dehydrated under high vacuum at 25 C. for 15 hours to give apasty white solid (0.39 grams, 30%) which was identified as the desiredtriethylammonium tris(pentafluorophenyl)allylborate salt.

[0246] Batch Reactor Polymerization Procedure

[0247] A 2 L stirred autoclave was charged with the desired amounts of amixed alkane solvent (Isopar® E, available from Exxon Chemicals, Inc.)and 1-octene comonomer. The reactor was heated to the polymerizationtemperature. Hydrogen was added by differential pressure expansion froma 75 ml addition tank.

[0248] The term “hydrogen delta psi” in Table 1 represents thedifference in pressure between the starting and final pressure in thehydrogen addition tank after adding hydrogen to the 2L reactorcontaining a total of approximately 1200 ml of solvent and 1-octene. Thereactor was heated to the polymerization temperature and was saturatedwith ethylene to the desired pressure. For these experiments, a constantethylene/solvent pressure of about 500 psig at a temperature of 140 C.corresponds to an ethylene concentration of about 8.4 percent by weightof the reactor contents. Metal complex and cocatalyst were mixed in adrybox by syringing the desired amount of 0.0050 M metal complexsolution (in Isopar® E or toluene) into a solution of the cocatalyst (inIsopar® E or toluene). This solution was then transferred to a catalystaddition tank and injected into the reactor. The polymerization wasallowed to proceed for the desired time and then the solution wasdrained from the bottom of the reactor and quenched with isopropanol.About 100 mg of a hindered phenolic antioxidant (Irganox® 1010,available from Ciba-Geigy corporation) was added and the polymer was airdried overnight. The residual solvent was removed in a vacuum ovenovernight. The results are shown in Table V and VA: TABLE V 1- Comp. H₂octene Isopar yield Effcny. Aluminum Ex. (psi) (gms) E (gms) (gms)(gm/gm Ti) (ppm) 10A* 50 38 820 39.6 330,689 0 11A* 25 38 820 70.1390,257 0 12A* 35 38 820 46.4 258,316 0 13A* 30 38 820 48.8 271,677 014A* 35 30 828 52.1 290,049 0 15A* 27 38 820 36.5 152,401 0 16A** 26 38820 47.8 266,110 0 17B*** 35 40 818 19.7 41,127 6850 18B*** 50 40 81819.7 41,127 6850 19B*** 25 40 818 18.3 38,204 7380

[0249] TABLE VA μmoles μmoles Irganox 1010 Comp. Ex. complex cocatalyst(ppm) 10A * 2.5 2.5 2500 11A * 3.75 3.75 1400 12A * 3.75 3.75 2200 13A *3.75 3.75 2000 14A * 3.75 3.75 1900 15A * 5 5 2700 16A * 3.75 3.75 200017B *** 10 5000 5000 18B *** 10 5000 5000 19B *** 10 5000 5500

[0250] The samples were each extruded via a Gas Extrusion Rheometer(GER) at 190 C. using 0.0296 inch diameter die (preferably 0.0143 inchdiameter die for high flow polymers, e.g. 50-100 MI or greater) havingL/D of 20:1 and entrance angle of 180 degrees, as shown in the attacheddrawing. The OGMF can easily be identified from the shear stress vs.shear rate plot where a sudden jump of shear rate occurs or whenthe-surface of the extrudate becomes very rough or irregular, or fromdeep ridges which can be-clearly detected by visual observation. OSMF ischaracterized by fine scale surface irregularities ranging from loss ofsurface gloss to the more severe form of matte or sharkskin which caneasily be seen using microscopy at a magnification of 40×.

[0251] Table VI displays the test results from Comparative Examples10-19: TABLE VI OGMF* OGMF* I₂ Shear Shear Comp. (gm/ (I₁₀/I₂) −Measured Rate Stress Ex. 10 min) I₁₀/I₂ 4.63 M_(w)/M_(n) (sec⁻¹) (MPa)10 4.52 5.62 0.99 1.856 706 0.344 11 0.67 6.39 1.76 1.834 118 0.323 122.24 5.62 0.99 1.829 300 0.323 13 2.86 5.60 0.97 1.722 397 0.323 14 3.255.66 1.03 1.827 445 0.302 15 1.31 5.67 1.04 1.718 227 0.302 16 1.97 5.71.07 1.763 275 0.302 17 0.36 12.98 8.35 5.934 <29 <0.086 18 0.40 13.348.71 5.148 <11.08 <0.086 19 0.13 13.25 8.62 6.824 <10.39 <0.086

[0252] Comparative Examples 10-16 were prepared using the catalystcomposition as described in U.S. Pat. No. 5,064,802 (Stevens et al.) asdescribed above. Comparative Examples 17-19 were prepared using thecatalyst composition described in U.S. Pat. No. 5,026,798 (Canich), asdescribed above. All of the Comparative Polymer Examples made using abatch reactor at an ethylene concentration of about 8.4 percent byweight of the reactor contents or more tested had onset of gross meltfracture at a shear stress of less than or equal to 0.344 MPa (3.44×10⁶dyne/cm²).

[0253] Interestingly, an ethylene concentration of about 8.4 percent isconsidered to be on the low side for a batch polymerization procedure,since it limits the reaction kinetics and slows the polymerizationprocess. Increasing the ethylene concentration in a batch reactor, as istaught in U.S. Pat. No. 5,026,798 (Canich), where the calculatedpropylene reactor concentrations for these ten examples ranges from alow of about 12.6 percent (Example 1) to a high of about 79 percent(Example 6), by weight of the reactor contents, results inpolymerization of polymers which do not have the novel structurediscovered by Applicants, as the OGMF data in Table VI demonstrates.Furthermore, the I₁₀/I₂ ratio of such comparative polymers made using abatch reactor at relatively high ethylene concentrations increases asthe molecular weight distribution, M_(w)/M_(n), increases, as isexpected based on conventional Ziegler polymerized polymers.

EXAMPLE 20 AND COMPARATIVE EXAMPLE 21

[0254] Blown film is fabricated from the two novel ethylene/1-octenepolymers of Examples 5 and 6 made in accordance with the presentinvention and from two comparative conventional polymers made accordingto conventional Ziegler catalysis. The blown films are tested forphysical properties, including heat seal strength versus heat sealtemperature (shown in FIG. 5 for Examples 20 and 22 and ComparativeExamples 21 and 23), machine (MD) and cross direction (CD) properties(e.g., tensile yield and break, elongation at break and Young'smodulus). Other film properties such as dart, puncture, tear, clarity,haze, 20 degree gloss and block are also tested.

[0255] Blown Film Fabrication Conditions

[0256] The improved processing substantially linear polymers of thepresent invention produced via the procedure described earlier, as wellas two comparative resins are fabricated on an Egan blown film lineusing the following fabrication conditions:

[0257] 2 inch (5 cm) diameter extruder

[0258] 3 inch (7.6 cm) die

[0259] 30 mil die gap

[0260] 25 RPM extruder speed

[0261] 460 F. (238 C.) melt temperature

[0262] 1 mil gauge

[0263] 2.7:1 Blow up ratio (12.5 inches (31.7 cm) layflat)

[0264] 12.5 inches (31.7 cm) frost line height

[0265] The melt temperature is kept constant by changing the extrudertemperature profile. Frost line height is maintained at 12.5 inches(31.7 cm) by adjusting the cooling air flow. The extruder output rate,back pressure and power consumption in amps are monitored throughout theexperiment The polymers of the present invention and the comparativepolymers are all ethylene/1-octene copolymers. Table VII summarizesphysical properties of the two polymers of the invention and for the twocomparative polymers: TABLE VII Comparative Comparative Property Example20 Example 21 Example 22 Example 23 I₂ (g/10 1 1 1 0.8 minutes) Density0.92 0.92 0.902 0.905 (g/cm³) I₁₀/I₂ 9.45 about 8 7.61 8.7 M_(w)/M_(n)1.97 about 4 2.09 about 5

[0266] Tables VIII and IX summarize the film properties measured forblown film made from two of these four polymers: TABLE VIII Blown filmproperties Comparative Comparative Example Example Example ExampleProperty 20 MD 20 CD 21 MD 21 CD Tensile yield 1391 1340 1509 1593 (psi)Tensile break 7194 5861 6698 6854 (psi) Elongation 650 668 631 723(percent) Young's 18,990 19,997 23,086 23,524 modulus (psi) PPT* tear5.9 6.8 6.4 6.5 (gms)

[0267] TABLE IX Comparative Property Example 20 Example 21 Dart A(grams) 472 454 Puncture (grams) 235 275 Clarity (percent transmittance)71 68 Haze (percent) 3.1 6.4 20 degree gloss 114 81 Block (grams) 148134

[0268] During the blown film fabrication, it is noticed that at the samescrew speed (25 rpm) and at the same temperature profile, the extruderback pressure is about 3500 psi at about 58 amps power consumption forComparative Example 21 and about 2550 psi at about 48 amps powerconsumption for Example 20, thus showing the novel polymer of Example 20to have improved processability over that of a conventions heterogeneousZiegler polymerized polymer. The throughput is also higher for Example20 than for Comparative Example 21 at the same screw speed. Thus,Example 20 has higher pumping efficiency than Comparative Example 21(i.e., more polymer goes through per turn of the screw).

[0269] As FIG. 5 shows, the heat seal properties of polymers of thepresent invention are improved, as evidenced by lower heat sealinitiation temperatures and higher heat seal strengths at a giventemperature, as compared with conventional heterogeneous polymers atabout the same melt index and density.

EXAMPLES 24 AND 25

[0270] The polymer products of Examples 24 and 25 are produced in acontinuous solution polymerization process using a continuously stirredreactor, as described in copending U.S. Pat. No. 5,272,236. The metalcomplex [C₅Me₄(SiMe₂N^(t)Bu)]TiMe₂ is prepared as described in U.S. Pat.No. 5,272,236 and the cocatalysts used are tris(pentafluorophenyl)borane (B:Ti ratio of 2:1) and MMAO (Al:Ti ratio of 4:1). For Example 24the ethylene concentration in the reactor is about 1.10 percent and forExample 25 the ethylene concentration in the reactor is about 1.02percent (percentages based on the weight of the reactor contents). Foreach Example, the reactor is run without hydrogen.

[0271] Additives (e.g., antioxidants, pigments, etc.) can beincorporated into the interpolymer products either during thepelletization step or after manufacture, with a subsequent re-extrusion.Examples 24 and 25 are each stabilized with 1250 ppm Calcium Stearate,200 ppm Irganox 1010, and 1600 ppm Irgafos 168. Irgafos™ 168 is aphosphite stabilizer and Irganox™ 1010 is a hindered polyphenolstabilizer (e.g., tetrakis [methylene3-(3,5-ditertbutyl-4-hydroxyphenylpropionate)]methane. Both aretrademarks of and made by Ciba-Geigy Corporation.

EXAMPLE 24 AND COMPARATIVE EXAMPLE 26

[0272] Example 24 is an ethylene/1-octene elastic substantially linearethylene polymer produced as described herein.

[0273] Comparative Example 26 is an ethylene/1-butene copolymertrademarked Exact™ made by Exxon Chemical containing butylated hydroxytoluene (BHT) and Irganox™ 1076 as polymeric stabilizers. Table Xsummarizes physical properties and rheological performance of Example 24and Comparative Example 26: TABLE X Comparative Property Example 24Example 26 I₂ (g/10 minutes) 3.3 3.58 Density (g/cm³) 0.870 0.878 I₁₀/I₂7.61 5.8 M_(w)/M_(n) 1.97 1.95 PI (kPoise) 3.2 8.4 Elastic Modulus @ 0.1rad/sec 87.7 8.3 (dyne/cm²) OSMF*, critical shear rate 660 250 (sec⁻¹)

[0274] Even though Example 24 and Comparative Example 26 have verysimilar molecular weight distributions (M_(w)/M_(n)), I₂ and density,Example 24 has a much lower processing index (PI) (38 percent of the PIof Comparative Example 26), a much higher shear rate at the onset ofsurface melt fracture (264 percent of shear rate at onset of OSMF) andan elastic modulus an order of magnitude higher than Comparative Example26, demonstrating that Example 24 has much better processability andhigher melt elasticity than Comparative Example 26.

[0275] Elastic modulus is indicative of a polymer's melt stability,e.g., more stable bubbles when making blown film and less neck-in duringmelt extrusion. Resultant physical properties of the finished film arealso higher.

[0276] Onset of surface melt fracture is easily identified by visuallyobserving the surface extrudate and noting when the extrudate startslosing gloss and small surface roughness is detected by using 40×magnification.

[0277] Dynamic shear viscosity of the polymers is also-used to showdifferences between the polymers and measures viscosity change versusshear rate. A Rheometrics Mechanical Spectrometer (Model RMS 800) isused to measure viscosity as a function of shear rate. The RMS 800 isused at 190 C. at 15 percent strain and a frequency sweep (i.e., from0.1-100 rad/sec) under a nitrogen purge. The parallel plates arepositioned such that they have a gap of about 1.5-2 mm. Data for Example24 and Comparative Example 26 are listed in Table XI and graphicallydisplayed in FIG. 6. TABLE XI Dynamic Viscosity Shear Rate DynamicViscosity (poise) (poise) for Comparative (rad/sec) for Example 24Example 26 0.1 28290 18990 0.1585 28070 18870 0.2512 27630 18950 0.398127140 18870 0.631 26450 18840 1 25560 18800 1.585 24440 18690 2.51223140 18540 3.981 21700 18310 6.31 20170 17960 10 18530 17440 15.8516790 16660 25.12 14960 15620 39.81 13070 14310 63.1 11180 12750 100 9280 10960

[0278] Surprisingly, Example 24 shows a shear thinning behaviour, eventhough Example 24 has a narrow molecular weight distribution. Incontrast, Comparative Example 26 shows the expected behaviour of anarrow molecular weight distribution polymer, with a flatterviscosity/shear rate curve.

[0279] Thus, elastic substantially linear ethylene polymers made inaccordance with the present invention (e.g. Example 24) have lower meltviscosity than a typical narrow molecular weight distribution linearcopolymer made by single site catalyst technology at the melt processingshear rate region of commercial interest. In addition, the novel elasticsubstantially linear ethylene polymers have a higher low shear/zeroshear viscosity than the Comparative linear polymer, thus demonstratingthat the copolymers of the invention have higher “green strength” whichis useful for forming and maintaining blended compositions such as thoseused in the wire and cable coating industry, where the compoundedmaterials must maintain their integrity at low or zero shear withoutsegregating the components.

EXAMPLE 25 AND COMPARATIVE EXAMPLE 27

[0280] Example 25 is an ethylene/1-octene elastic substantially linearethylene polymer produced in a continuous solution polymerizationprocess as described herein.

[0281] Comparative Example 27 is an ethylene/propene copolymer made byMitsui PetroChemical Corporation and trademarked Tafmer™ P-0480. TableXII summarizes physical properties and Theological performance of thesetwo polymers: TABLE XII Comparative Property Example 25 Example 27 I₂(g/10 minutes) 1.01 1.1 Density (g/cm³) 0.870 0.870 I₁₀/I₂ 7.62 6.06M_(w)/M_(n) 1.98 1.90 PI (kPoise) 7.9 27.4 Elastic Modulus @ 0.1 964567.7 rad/sec (dyne/cm²) OSMF*, critical shear rate 781 105 (sec⁻¹)

[0282] Even though Example 25 and Comparative Example 27 have similarlynarrow molecular weight distributions (M_(w)/M_(n)), I₂, and density,Example 25 has a PI which is 28 percent of that of Comparative Example27, a 743 percent of the shear rate at the onset of surface meltfracture and a higher elastic modulus than Comparative Example 27,demonstrating that Example 24 has much better processability thanComparative Example 27. Onset of surface melt fracture is easilyidentified by visually observing the surface extrudate and noting whenthe extrudate starts losing gloss and small surface roughness isdetected by using 40× magnification.

EXAMPLES 28-37

[0283] Examples 28-35 are ethylene/propene copolymers made using theconstrained geometry catalyst described herein and in a continuoussolution polymerization process. Examples 36 and 37 areethylene/1-butene copolymers made using the constrained geometrycatalyst described herein and in a continuous solution polymerizationprocess. Examples 28-37 each contained approximately 1250 ppm calciumstrearate, 200 ppm Irganox 1010. These polymers did not, however,contain a secondary antioxidant (e.g. a phosphite). The low level ofphenol (i.e. 200 ppm Irganox 1010) coupled with the lack of thesecondary antioxidant may have contributed to the lower melt fractureperformance of some of the polymers shown in Table XV. It is well knownthat thermally processing polyethylene polymers, especially in thepresence of oxygen, can lead to oxidative crosslinking and extrusionvariation, i.e. melt fracture. Table XIII and XIIIA describe thepolymerization conditions and Table XIV describes the resultant polymerphysical properties for Examples 28-35: TABLE XIII Reactor ethyleneEstimated conc. reactor PE Hydrogen/ (weight conc. (weight Ethylene flowethylene ratio Ex. percent) percent) rate (lbs/hr) (mole percent) 28 5.36.0 3.19 0.048 29 4.2 7.3 3.19 0.024 30 4.0 8.9 3.19 0.028 31 3.5 9.33.18 0.024 32 2.5 10.6 3.20 0.027 33 2.6 10.7 3.18 0.007 34 1.3 10.53.19 0.027 35 1.0 10.9 3.19 0.010

[0284] TABLE XIIIA Diluent/ Ethylene ethylene Comonomer/olefin Ex.Reactor temp (C.) Conversion % ratio ratio* 28 170 51 8.2 25.5 29 172 618.1 24.0 30 171 67 7.1 16.6 31 171 71 7.2 20.1 32 170 79 7.1 15.6 33 17378 7.1 16.7 34 145 88 8.2 17.8 35 158 91 8.2 18.8

[0285] TABLE XIV I₂ (gms/10 Density Ex. minutes) I₁₀/I₂ (gm/cm³)M_(w)/M₃ 28 1.08 7.8 0.9176 2.00 29 1.02 8.8 0.9173 2.17 30 0.82 9.20.9175 2.08 31 0.79 9.4 0.9196 2.04 32 1.01 10.6 0.9217 2.09 33 0.8312.4 0.9174 2.31 34 0.54 15.2 0.9201 2.12 35 0.62 15.6 0.9185 2.32

[0286]FIG. 7 graphically displays a best fit line drawn through a plotof the I₁₀/I₂ ratio for the ethylene/propene substantially linearpolymers of Examples 28-35 as a function of ethylene concentration inthe polymerization reactor. Surprisingly, in contrast to conventionalZiegler polymerized polymers and in contrast to a batch polymerizationusing the same catalyst and relatively high ethyelne concentrations, asthe ethylene concentration in the reactor decreases using a continuouspolymerization process, the I₁₀/I₂ ratio (indicating the amount of longchain branching in the novel substantially linear polymers) increases,even though the molecular weight distribution, M_(w)/M_(n), remains verynarrow and essentially constant at about 2.

[0287] Table 15 shows the critical shear stress and critical shear rateat OGMF and OSMF for Examples 28-35: TABLE XV Example OSMF OGMF 28(shear stress) 2.15 × 10⁶ dyne/cm² 4.09 × 10⁶ dyne/cm² 28 (shear rate)129.8 sec⁻¹ 668.34 sec⁻¹ 29 (shear stress) 1.94 × 10⁶ dyne/cm² 4.3 × 10⁶dyne/cm² 29 (shear rate) 118.8 sec⁻¹ 652.1 sec⁻¹ 30 (shear stress) 1.08× 10⁶ dyne/cm² 4.3 × 10⁶ dyne/cm² 30 (shear rate) 86.12 sec⁻¹ 650.7sec⁻¹ 31 (shear stress) 1.08 × 10⁶ dyne/cm² >4.3 × 10⁶ dyne/cm² 31(shear rate) 90.45 sec⁻¹ >6.83 sec⁻¹ 32 (shear stress) 1.94 × 10⁶dyne/cm² 3.66 × 10⁶ dyne/cm² 32 (shear rate) 178.2 sec⁻¹ 673 sec⁻¹ 33(shear stress) 2.15 × 10⁶ dyne/cm² about 3.23 × 10⁶ dyne/cm² 33 (shearrate) 235.7 sec⁻¹ about 591 sec⁻¹ 34 (shear stress) 1.94 × 10⁶ dyne/cm²3.44 × 10⁶ dyne/cm² 34 (shear rate) 204.13 sec⁻¹ 725.23 sec⁻¹ 35 (shearstress) 1.94 × 10⁶ dyne/cm² about 3.26 × 10⁶ dyne/cm² 35 (shear rate)274.46 sec⁻¹ 637.7 sec⁻¹

[0288] Table XVI and XVIA describe the polymerization conditions andTable XVII describes the resultant polymer physical properties forethylene/1-butene copolymer Examples 36 and 37: TABLE XVI Reactorethylene Reactor PE conc. conc Hydrogen/ (weight (weight Ethylene flowethylene ratio Ex. percent) percent) rate (lbs/hr) (mole percent) 36 5.35.8 3.20 0.035 37 1.3 10.8 3.19 0.010

[0289] TABLE XVIA Ethylene Comonomer/ Diluent/ Conversion olefin Ex.Reactor temp (C.) Ethylene Ratio (%) ratio* 36 170 8.1 51 24.2 37 1528.2 87 17.1

[0290] TABLE XVII I₂ (gms/10 Density Ex. minutes) I₁₀/I₂ (gm/cm³)M_(w)/M_(n) 36 0.59 7.5 0.9201 2.06 37 1.03 11.4 0.9146 2.22

[0291] The data in Tables XVI, XVIA and XVII show that as the ethyleneconcentration in the reactor decreases while using the constrainedgeometry catalyst as described herein, the I₁₀/I₂ ratio of the novelsubstantially linear polymers increases, indicating the amount of longchain branching in the novel polymers, even while the molecular weightdistribution, M_(w)/M_(n), of the novel polymers remains narrow atessentially about 2.

[0292] Table XVIII shows the critical shear stress and critical shearrate at OGMF and OSMF for Examples 36 and 37: TABLE XVIII Example OSMFOGMF 36 (shear stress) 1.94 × 10⁶ dyne/cm² 4.09 × 10⁶ dyne/cm² 36 (shearrate) 52.3 sec⁻¹ 234.45 sec⁻¹ 37 (shear stress) 1.08 × 10⁶ dyne/cm² 3.01× 10⁶ dyne/cm² 37 (shear rate) 160.5 sec⁻¹ 493.9 sec⁻¹

COMPARATIVE EXAMPLE 38

[0293] An ethylene polymer, as described in U.S. Pat. No. 5,218,071, ispolymerized according to the teachings of that patent and tested formelt fracture properties.

[0294] All catalyst manipulations were performed under anhydrous,anaerobic conditions in an inert atmosphere box. The solvents, tolueneand Isopar E, and the comonomer, octene-1, were thoroughly dried anddeaerated beore use. poly(methylalumioxane) (PMAO) was obtained fromAKZO Chemicals Inc. as a 1.55 M Al in toluene solution and used asreceived. The metallocene ethylenebis(indenyl)hafnium dichloride wasobtained rom Schering A. G. as a solid. This metallocene is known tocontain 0.2 weight percent Zirconium contamination. A slurry of thehafnium complex was prepared from this solid (0.253 g; 0.5 mmol; 0.010M) and 50 mL toluene. The slurry was thoroughly stirred overnight priorto use.

[0295] A one gallon, stirred autoclave reactor ws charged with Isopar E(2.1 L) and octene-1 (175 mL) and the contents heated to 80C. Uponreaching temperature, a sample of the PMAO (26.8 mL; 40.0 mmol Al) intoluene was pressured into the reactor from a 75 mL cylinder using anitrogen flush. After a few minutes, an aliquot of the metalloceneslurry (4.0 mL; 0.040 mmol; Al:Hf=1000:1) was flushed into the reactorin a similar manner. Ethylene was continuously supplied to the reactorat a rate of 17 g/min to initiate polymerization. The ethylene flow wasmaintained for ten minutes and during the latter part of thepolymerization the flow rate slowed as the pressure approached asetpoint of 100 psig. After this time, the ethylene supply was shut offand the contents of the reactor transferred by pressure to a glass resinkettle containing a small amount of antioxidant (0.30 g Irgaphos 168;0.07 g Irganox 1010). The solvent was slowly allowed to evaporate andthe polymer obtained form the solution was dried under vacuum at 50 C.for 72 h. The yield of the product was 159 g or an efficiency of 3975 gPE/mmol Hf.

[0296] The recovered polymer had a M_(w)=1.341×10⁵, M_(n)=5.65×10⁴,M_(w)/M_(n)=2.373, density (measured in a gradien column)=0.8745 g/cc,I₂=0.63 g/10 min., I₁₀/I₂=15.9, and had two distinct melting peaks (asshown in FIG. 8). The polymer showed two peak melting points, one at30.56 C. and the other at 102.55 C. The polymer also showed two peakcrystallization points, one at 9.47 C. and the other at 81.61 C.

[0297] Melt fracture was determined using the GER at 190 C. with a diehaving a diameter of 0.0145 inches and an L/D=20.

We claim:
 1. An ethylene polymer having: a) a melt flow ratio,I₁₀/I₂,≧5.63, b) a molecular weight distribution, M_(w)/M_(n), definedby the equation: M _(w) /M _(n)#(I ₁₀ /I ₂)≦4.63, and c) a criticalshear stress at onset of gross melt fracture greater than about 4×10⁶dyne/cm², and d) a single melting point as determined by differentialscanning calorimetry between −30 C. and 150 C.
 2. An ethylene polymerhaving: a) a melt flow ratio, I₁₀/I₂,≧5.63, b) a molecular weightdistribution, M_(w)/M_(n), defined by the equation: M _(w) /M _(n)#(I ₁₀/I ₂)≦4.63, and c) a critical shear rate at onset of surface meltfracture at least 50 percent greater than the critical shear rate at theonset of surface melt fracture of a linear ethylene polymer having anI₂, M_(w)/M_(n) and density within ten percent of the ethylene polymer,and d) a single melting point as determined by differential scanningcalorimetry between −30 C. and 150 C.
 3. An ethylene polymer having: a)a melt flow ratio, I₁₀/I₂,≧5.63, b) a molecular weight distribution,M_(w)/M_(n) of from about 1.5 to about 2.5, and c) a single melting peakas determined by DSC between −30 C. and 150 C.
 4. An ethylene polymerhaving: a) a melt flow ratio, I₁₀/I₂,≧5.63, b) a molecular weightdistribution, M_(w)/M_(n) of from about 1.5 to about 2.5, c) a criticalshear rate at onset of surface melt fracture of at least 50 percentgreater than the critical shear rate at the onset of surface meltfracture of a linear ethylene polymer having an I₂, M_(w)/M_(n) anddensity within ten percent of the ethylene polymer, and d) a singlemelting point as determined by differential scanning calorimetry between−30 C. and 150 C.
 5. An ethylene polymer having (i) a critical shearrate at onset of surface melt fracture of at least 50 percent greaterthan the critical shear rate at the onset of surface melt fracture of alinear ethylene polymer having an I₂, M_(w)/M_(n) and density within tenpercent of the ethylene polymer, and (ii) a single melting point asdetermined by differential scanning calorimetry between −30 C. and 150C.
 6. An ethylene polymer characterized in that the ethylene polymer isa substantially linear ethylene polymer having: (a) from abou 0.01 toabout 3 long chain branches/1000 total carbons and (b) a critical shearstress at onset of gross melt-fracture of greater than about 4×10⁶dyne/cm², and (c) a single melting point as determined by differentialscanning calorimetry between −30 C. and 150 C.
 7. An ethylene polymercharacterized in that the ethylene polymer is a substantially linearethylene polymer having: (a) from about 0.01 to about 3 long chainbranches/1000 total carbons, (b) a critical shear rate at onset ofsurface melt fracture of at least 50 percent greater than the criticalshear rate at the onset of surface melt fracture of a linear ethylenepolymer having an I₂, M_(w)/M_(n) and density within ten percent of theethylene polymer, and (c) a single melting point as determined bydifferential scanning calorimetry between −30 C. and 150 C.
 8. Anethylene polymer characterized in that the ethylene polymer is asubstantially linear ethylene polymer having: (a) from about 0.01 tabout 3 long chain branches/1000 total carbons, (b) a melt flow ratio,I₁₀/I₂,≧5.63, and (c) a molecular weight distribution, M_(w)/M_(n) fromabout 1.5 to about 2.5, and d) a single melting point as determined bydifferential scanning calorimetry between −30 C. and 150 C.
 9. Theethylene polymer of any of claims 1-8, wherein the ethylene polymer is:(A) an ethylene homopolymer, or (B) an interpolymer of ethylene with atleast one C₄-C₁₈ diolefin.
 10. The ethylene polymer of any of claims1-8, wherein the ethylene polymer is selected from the group consistingof: (A) an ethylene homopolymer, or (B) an interpolymer of ethylene withat least one C₃-C₂₀ alpha-olefin.
 11. The ethylene polymer of any ofclaims 1-7 in which the M_(w)/M_(n) is less than about
 5. 12. Theethylene polymer of any of claims 1-7 wherein the ethylene polymer has aM_(w)/M_(n) less than about 3.5.
 13. The ethylene polymer of any ofclaims 1-7 in which the M_(w)/M_(n) is between about 1.5 and about 2.5.14. The ethylene polymer of any of claims 1-7 wherein the ethylenepolymer has a M_(w)/M_(n) from about 1.7 to about 2.3.
 15. The ethylenepolymer of any of claims 1-5 wherein the ethylene polymer is asubstantially linear ethylene polymer having from about 0.01 to about 3long chain branches/1000 total carbons.
 16. The ethylene polymer of anyof claims 1-8 further characterized as containing less than about 20 ppmaluminum.
 17. The ethylene polymer of any of claims 1-8 furthercharacterized as containing less than about 10 ppm aluminum.
 18. Theethylene polymer of any of claims 1-8 further characterized ascontaining less than about 5 ppm aluminum.
 19. A process of preparing asubstantially linear ethylene polymer having a melt flow ratio,I₁₀/I₂,≧5.63, a molecular weight distribution, M_(w)/M_(n), defined bythe equation: M_(w)/M_(n)≦(I₁₀/I₂)−4.63, and a single melting point asdetermined by differential scanning calorimetr between −30 C. and 150 C.said process characterized by continuously contacting ethylene alone orethylene and one or more C₃-C₂₀ alpha-olefins with a catalystcomposition under polymerization conditions, wherein said catalystcomposition is characterized as:

wherein: M is a metal of group 3-10, or the Lanthanide series of thePeriodic Table of the Elements; Cp* is a cyclopentadienyl or substitutedcyclopentadienyl group bound in an O⁵ bonding mode to M; Z is a moietycomprising boron, or a member of group 14 of the Periodic Table of theElements, and optionally sulfur or oxygen, said moiety having up to 20non-hydrogen atoms, and optionally Cp* and Z together form a fused ringsystem; X independently each occurrence is an anionic ligand group orneutral Lewis base ligand group having up to 30 non-hydrogen atoms; n is0, 1, 2, 3, or 4 and is 2 less than the valence of M; and Y is ananionic or nonanionic ligand group bonded to Z and M comprisingnitrogen, phosphorus, oxygen or sulfur and having up to 20 non-hydrogenatoms, optionally Y and Z together form a fused ring system, and (b) anactivating cocatalyst.
 20. The process of claim 14 wherein (a)corresponds to the formula:

wherein: R′ each occurrence is independently selected from the groupconsisting of hydrogen, alkyl, aryl, silyl, germyl, cyano, halo andcombinations thereof having up to 20 non-hydrogen atoms; X eachoccurrence independently is selected from the group consisting ofhydride, halo, alkyl, aryl, silyl, germyl, aryloxy, alkoxy, amide,siloxy, neutral Lewis base ligands and combinations thereof having up to20 non-hydrogen atoms; Y is —O—, —S—, —NR*—, —PR*—, or a neutral twoelectron donor ligand selected from the group consisting of OR*, SR*,NR*₂ or PR*₂; M is a metal of group 3-10, or the Lanthanide series ofthe Periodic Table of the Elements; and Z is SiR*₂, CR*₂, SiR*₂SiR*₂,CR*₂CR*₂, CR*═CR*, CR*₂SiR*₂, GeR*₂,BR*, BR*₂; wherein R* eachoccurrence is independently selected from the group consisting ofhydrogen, alkyl, aryl, silyl, halogenated alkyl, halogenated aryl groupshaving up to 20 non-hydrogen atoms, and mixtures thereof, or two or moreR* groups from Y, Z, or both Y and Z form a fused ring system; and n is1 or
 2. 21. The process of claim 14 wherein (a) is an amidosilane oramidoalkanediyl compound corresponding to the formula:

wherein: M is titanium, zirconium or hafnium, bound in an eta⁵ bondingmode to the cyclopentadienyl group; R′ each occurrence is independentlyselected from the group consisting of hydrogen, silyl, alkyl, aryl andcombinations thereof having up to 10 carbon or silicon atoms; E issilicon or carbon; X independently each occurrence is hydride, halo,alkyl, aryl, aryloxy or alkoxy of up to 10 carbons; m is 1 or 2; and nis 1 or
 2. 22. The process of any of the claims 19 in which component b)is an inert, noncoordinating boron cocatalyst.
 23. The process of any ofthe claims 19 in which the cocatalyst is tris(pentafluorophenyl)borane.24. The process of any of the claims 19 wherein the process is: (A) agas phase process, or (B) a suspension process, or (C) a solutionprocess, or (D) a slurry process.
 25. The solution process of claim 24wherein the polymerization conditions comprise a reaction temperatureand ethylene concentration sufficient to form the substantially linearethylene polymer.
 26. The process of claim 25 wherein the polymerizationconditions comprise a reaction temperature and ethylene concentrationsufficient to form a substantially linear ethylene polymer having aI₁₀/I₂ of at least about
 8. 27. The process of claim 26 wherein thepolymerization conditions comprise a reaction temperature and anethylene concentration sufficient to form the substantially linearethylene polymer, wherein the polymer has a I₁₀/I₂ of at least about 9.28. The product obtainable by any of the processes of claims
 19. 29. Acomposition comprising an ethylene polymer and at least one othernatural or synthetic polymer, wherein the ethylene polymer ischaracterized as the ethylene polymer of any of claims 1-8.
 30. Acomposition comprising an ethylene polymer and at least one othernatural or synthetic polymer, wherein the ethylene polymer ischaracterized as: (A) an ethylene/alph-olefin substantially linearethylene polymer, or (B) a substantially linear ethylene homopolymer.31. The composition of claim 30 wherein the synthetic polymer is aconventional Ziegler polymerized ethylene/alpha-olefin polymer.
 32. Afabricated article comprising an ethylene polymer, characterized in thatthe ethylene polymer is the ethylene polymer of any of claims 1-8. 33.The fabricated article of claim 32 wherein the article is: (A) a film,or (B) a fiber, or (C) a sheet, or (D) a woven fabric, or (E) a nonwovenfabric, or (F) a molded article, or (G) a wire and cable coating. 34.The fabricated article of claim 33 wherein the film is a blown film. 35.The blown film of claim 33 wherein the ethylene polymer is anethylene/alpha-olefin copolymer having a density from 0.90 g/cm³ to 0.92g/cm³.
 36. The blown film of claim 35 wherein the ethylene/alpha-olefincopolymer has a molecular weight distribution, M_(w)/M_(n), from about1.5 to about 2.5.
 37. The blown film of claim 36 wherein the film has aheat seal strength equal to or higher than a film made from aheterogeneous Ziegler polymerized polymer at the same heat sealtemperature, wherein the melt index, molecular weight distribution anddensity of the substantially linear ethylene polymer and theheterogeneous Ziegler polymerized polymer are within ten percent of oneanother.
 38. The process of any of claim 19, wherein the polymerizationtemperature is from 20 C. to 250 C., wherein the ethylene concentrationis from 6.7 to 12.5 percent by weight of the reactor contents, andwherein the concentration of the substantially linear ethylene polymeris less than 5 percent by weight of the reactor contents.
 39. Theprocess of claim 38 wherein the ethylene concentration is furthercharacterized as not more than 8 percent of the reactor contents to forma substantially linear ethylene polymer having a I₁₀/I₂ of at leastabout
 8. 40. The process of claim 38 wherein the ethylene concentrationis further characterized as not more than about 6 percent of the reactorcontents to form a substantially linear ethylene polymer having a I₁₀/I₂of at, least about
 9. 41. The product obtainable by any one of theprocesses of claims
 19. 42. A composition comprising an ethylene polymerand at least one other natural or synthetic polymer, wherein theethylene polymer is characterized as the substantially linear ethylenepolymer of any of claims
 19. 43. The composition of claim 42 wherein thesynthetic polymer is a conventional Ziegler polymerizedethylene/alpha-olefin polymer.
 44. A fabricated article comprising anethylene polymer, characterized in that the ethylene polymer is thesubstantially linear ethylene polymer of any of claims
 19. 45. Thefabricated article of claim 44 wherein the article is: (A) a film, or(B) a fiber, or (C) a sheet, or (D) a woven fabric, or (E) a nonwovenfabric, or (F) a molded article, or (G) a wire and cable coating. 46.The fabricated article of claim 45 wherein the film is a blown film. 47.The blown film of claim 46 wherein the substantially linear ethylenepolymer is an ethylene/alpha-olefin copolymer having a density from 0.9g/cm² to 0.92 g/cm³.
 48. The blown film of claim 47 wherein theethylene/alpha-olefin copolymer has a molecular weight distribution,M_(w)/M_(n), from about 1.5 to about 2.5.
 49. The blown film of claim 48wherein the film has a heat seal strength equal to or higher than a filmmade from a heterogeneous Ziegler polymerized polymer at the same heatseal temperature, wherein the melt index, polydispersity and density ofthe substantially linear ethylene polymer and the heterogeneous Zieglerpolymerized polymer are within ten percent of one another.
 50. Thesubstantially linear ethylene polymer of any of claims 19 wherein thesubstantially linear ethylene polymer is an ethylene homopolymer. 51.The substantially linear ethylene polymer of any of claims 19 whereinthe substantially linear ethylene polymer is an interpolymer of ethylenewith at least one a C₃-C₂₀ alpha-olefin.
 52. The substantially linearethylene polymer of any of claims 19 wherein the substantially linearethylene polymer is a copolymer of ethylene and a C₃-C₂₀ alpha-olefin.53. The substantially linear ethylene polymer of any of claims 19wherein the substantially linear ethylene polymer is furthercharacterized as a copolymer of ethylene and 1-octene.
 54. The polymerof any one of claims 1-8 in which the density is at least about 0.87g/cm².
 55. The polymer of any one of claims 1-8 in which the density isat least about 0.90 g/cm².
 56. The polymer of any one of claims 1-8 inwhich the density do not exceed about 0.94 g/cm².
 57. The polymer of anyone of claims 1-8 in which the density do not exceed about 0.92 g/cm².58. The polymer of any one of claims 1-8 further characterized as havinga melt tension of at least about 2 grams.
 59. The polymer of any one ofclaims 1-8 further characterized as having a processing index of lessthan about 15 kpoise.
 60. The polymer of any one of claims 1-8 in theform of a pellet.
 61. The polymer of any one of claims 1-8 furthercharacterized as being pelletizable at ambient temperature.
 62. Thepolymer of any one of claims 1-8 further characterized as beingpelletizable at cool water temperatures.
 63. The polymer of any one ofclaims 1-8 further characterized as comprising at least one antioxidant.64. The polymer of any one of claims 1-8 further characterized ascomprising at least one phenolic antioxidant and at least one phosphateantioxidant.